By Adam Smart, Ecokeys Support Engineer — Last updated 2 September 2026

If you are comparing Office 2021 Professional Plus with Office 365, there is one important fact that now needs to come before the usual feature and price comparison:

Microsoft support for Office 2021 ends on 13 October 2026.

That changes the decision considerably. Office 2021 is still usable today, and existing installations will not suddenly stop opening after the support deadline, but Microsoft will no longer provide security updates, bug fixes or technical support once the product reaches end of support.

There is another terminology change worth clearing up. For most home and small-business customers, the subscription products previously commonly called Office 365 are now branded Microsoft 365.

First: Is Office 365 Now Microsoft 365?

For most home users and small businesses, yes.

Microsoft changed the names of many Office 365 subscription products to Microsoft 365 several years ago. For example, Office 365 Personal became Microsoft 365 Personal, while Office 365 Home became Microsoft 365 Family.

Some enterprise, education and government products have continued to use Office 365 branding, but if you are an individual or small business comparing a traditional installed Office suite with a subscription, Microsoft 365 is generally the current terminology you will see.

The Most Important Difference in 2026: Office 2021 Is Near End of Support

Office 2021 was released in October 2021. Microsoft has confirmed that its support lifecycle ends on 13 October 2026.

After that date Microsoft says Office 2021 will no longer receive:

• Security updates.
• Bug fixes.
• Software updates from Microsoft Update.
• Microsoft technical support for newly discovered problems.

Your Word, Excel, PowerPoint and other Office 2021 applications are not expected to simply stop opening on 14 October. The issue is that the software will then be operating outside Microsoft's supported lifecycle.

This matters much more in September 2026 than it did when this comparison was first published in 2024.

If you already own Office 2021, there is no need to panic or uninstall it today. However, it is sensible to decide what you will use next rather than waiting until after support has ended.

Office 2021 Pro Plus vs Microsoft 365 at a Glance

What Is Office 2021 Professional Plus?

Office 2021 Professional Plus is part of Microsoft's 2021 generation of desktop Office software.

It provides locally installed Office applications rather than access being dependent on maintaining a Microsoft 365 subscription.

Depending on the exact Office 2021 Professional Plus licence and deployment, applications can include:

• Microsoft Word 2021.
• Microsoft Excel 2021.
• Microsoft PowerPoint 2021.
• Microsoft Outlook 2021.
• Microsoft Access 2021.
• Microsoft Publisher 2021.

One advantage of this type of Office release is predictability. The core application version remains Office 2021 rather than continually changing into new generations of Office functionality.

That can appeal to users who prefer installed desktop software and do not need Microsoft 365's wider cloud services.

Office 2021 does receive updates — until support ends

An important correction to some older Office comparisons is that a non-subscription Office release is not necessarily frozen from the day it is installed.

Office 2021 has continued to receive security, reliability and other servicing updates during its supported lifecycle.

What it does not receive is the same continual stream of new subscription features provided to qualifying Microsoft 365 customers.

The bigger issue now is that Office 2021's supported lifecycle is almost finished.

What “non-subscription” actually means

It is better to describe Office 2021 as a non-subscription or perpetual Office release rather than using phrases such as “lifetime Office” or suggesting that Microsoft supports the software forever.

The software does not require a Microsoft 365 monthly or annual subscription simply to remain an Office 2021 release, but every Office version still has a Microsoft product lifecycle.

What Is Microsoft 365?

Microsoft 365 is Microsoft's subscription-based productivity platform.

Qualifying Microsoft 365 plans can provide the familiar desktop applications such as Word, Excel, PowerPoint and Outlook, but the subscription can extend well beyond the desktop applications themselves.

Features depend on the plan, but Microsoft 365 can include:

• Continuously updated desktop Office applications.
• OneDrive cloud storage.
• Use across PCs, Macs, phones and tablets.
• Microsoft Defender features on qualifying consumer plans.
• Collaboration and file-sharing features.
• Additional Outlook features.
• AI-powered Microsoft 365 features on qualifying plans.
• Business services such as Exchange email and Teams on relevant business plans.

This means the main Microsoft 365 question is not simply whether Word or Excel is “better”. You are paying for an ongoing combination of applications, updates, cloud storage and connected services.

Microsoft 365 changes over time

One advantage of the subscription model is that Microsoft can introduce new features without requiring you to buy the next traditional Office generation.

The other side of that arrangement is that you must maintain the subscription to retain the full subscription benefits.

This makes Microsoft 365 particularly attractive when you actively use the services around Office rather than only opening Word or Excel occasionally on one PC.

Office 2021 vs Microsoft 365 Cost in 2026

This is another area where older comparisons can be misleading because Microsoft 365 subscription prices have changed.

As of September 2026, Microsoft's UK website lists:

Microsoft also offers other consumer and business subscription plans, so these prices should not be treated as the cost of every Microsoft 365 option.

Business pricing also depends on the plan selected, the number of users and the billing arrangement.

Do not compare only the first-year price

A subscription-versus-non-subscription comparison needs to consider what happens over several years.

For example, at the current £84.99 annual price, Microsoft 365 Personal costs:

• £84.99 over one year.
• £169.98 over two years if the price remains unchanged.
• £254.97 over three years if the price remains unchanged.

That does not automatically make Microsoft 365 poor value. You are also receiving its cloud storage, supported applications, updates and other subscription services during that period.

The relevant question is whether you actually use those benefits.

When Microsoft 365 Makes More Sense

When a Non-Subscription Office Version Makes More Sense

Some users simply do not need the wider Microsoft 365 platform.

A non-subscription Office release can make more sense when:

• You mainly work on one Windows PC.
• You only need the installed desktop Office applications.
• You already use another cloud storage provider.
• You do not need Microsoft 365's newest feature additions.
• You prefer not to maintain another monthly or annual subscription.
• You use Office in an environment where local desktop applications are preferable.

However, in September 2026 this does not mean Office 2021 is automatically the correct version to choose.

That is where Office 2024 becomes important.

What Should You Do If You Already Have Office 2021?

If Office 2021 is already installed and working, there is no requirement to remove it immediately simply because its end-of-support date is approaching.

Your priority should be to plan what happens next.

Before 13 October 2026

• Make sure Office 2021 is fully updated.
• Confirm which Office edition you actually have installed.
• Check whether any business processes depend on Access, Publisher, Outlook add-ins, Excel macros or other specialist functionality.
• Decide whether you want to move to Microsoft 365 or another non-subscription Office release.
• Allow time to test important documents, spreadsheets and add-ins before changing software.

After 13 October 2026

Office 2021 applications may continue to function, but Microsoft will no longer issue security fixes for newly discovered Office 2021 vulnerabilities.

For a personal computer that rarely handles sensitive information, an individual may choose to tolerate that risk temporarily while planning an upgrade.

For a business PC, a computer handling customer information or any security-sensitive environment, remaining indefinitely on unsupported productivity software is much harder to justify.

Should You Buy Office 2021 in September 2026?

For most people choosing a new Office installation today, Office 2021 is difficult to recommend as a long-term choice because its Microsoft support lifecycle ends on 13 October 2026.

That does not make an existing Office 2021 licence useless. It means the context has changed.

A purchaser specifically needing Office 2021 for a temporary compatibility requirement may still have a reason to use it, but someone simply looking for “Office without a subscription” should compare the current Office generation instead.

Where Does Office 2024 Fit Into This Decision?

When this article was originally written in 2024, Office 2021 was still Microsoft's current non-subscription Office generation.

That is no longer the case.

Office 2024 is now available for customers who want locally installed Office applications without moving to a Microsoft 365 subscription.

Microsoft lists the Office 2024 lifecycle through 9 October 2029, compared with 13 October 2026 for Office 2021.

If the real decision you are making is “subscription or one-time Office?”, comparing Microsoft 365 with Office 2024 is now more useful than treating Office 2021 as the default alternative.

Our Office 2024 vs Office 2021 guide looks specifically at the differences between the two non-subscription generations.

Office 2021 or Microsoft 365: Which Is Better for Different Users?

What About Free Microsoft 365 Apps?

You may not need to buy either option if your requirements are basic.

Microsoft provides web versions of Word, Excel, PowerPoint and other Microsoft 365 applications that can be used through a browser with a Microsoft account.

These browser versions do not provide every feature found in the full desktop applications, but they can be enough for:

• Basic Word documents.
• Simple spreadsheets.
• Viewing and making light edits to files.
• Occasional PowerPoint work.
• Users who only need Office infrequently.

Before paying for software, check whether the free web applications already cover what you actually do.

Avoid Suspiciously Cheap Microsoft 365 Accounts

There is an important difference between purchasing a legitimate Microsoft 365 subscription and purchasing access to an unknown Microsoft account from a third party.

Be cautious of websites offering extremely cheap “Microsoft 365 lifetime accounts”, shared accounts, education accounts or login credentials that you did not create yourself.

Your cloud files can be important. If you are going to store documents in OneDrive, make sure the Microsoft account belongs to you or your organisation and that you control its recovery information and security settings.

Our View in September 2026

Office 2021 and Microsoft 365 originally represented a straightforward choice between a traditional Office release and a subscription.

That comparison is now incomplete because Office 2021 reaches end of support on 13 October 2026.

If you already use Office 2021, there is still time to plan your next step. The applications will not suddenly disappear when support ends, but continuing indefinitely without security updates is not a good long-term strategy.

If you are choosing today:

• Choose Microsoft 365 when you value multiple-device use, OneDrive storage, ongoing feature updates and the wider Microsoft service ecosystem.
• Consider Office 2024 when you want installed desktop Office applications without an ongoing subscription.
• Choose Office 2021 only for a specific short-term or compatibility reason while understanding how little supported lifecycle remains.

If you are unsure which non-subscription version or edition suits you, you can compare the current Microsoft Office options available from EcoKeys rather than choosing based purely on the year printed on the product.

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