Office 2021 or Microsoft 365: the difference comes down to how you pay. Office 2021 is a perpetual licence: you pay once, the applications are yours on one PC, but they no longer evolve. Microsoft 365 is a subscription: you pay every year for applications that are always up to date, 1 TB of OneDrive storage, Copilot and up to five signed-in devices. For standard office use on a single computer, a perpetual licence works out much cheaper over time; for several devices, the cloud or AI, the subscription makes sense.
One date changes the picture, however: Office 2021 support ended on 13 October 2026. We take this into account in the recommendations below, with Office 2024 as the perpetual alternative.
What is the difference between Office 2021 and Microsoft 365?
Both give access to the same core applications (Word, Excel, PowerPoint, Outlook), with an almost identical interface day to day. What separates them is the licensing model and everything that follows from it.
| Criterion | Office 2021 (perpetual) | Microsoft 365 Personal |
|---|---|---|
| Payment | Once | Every month or every year |
| Period of use | Unlimited | As long as the subscription is paid |
| New features | None (frozen version) | Continuous |
| Security updates | Ended 13 October 2026 | Continuous |
| Devices | 1 PC per licence (or 3, 5 depending on the offer) | 5 signed in at the same time |
| Operating systems | Windows or Mac depending on the edition | Windows, Mac, iOS, Android |
| OneDrive storage | 5 GB free | 1 TB |
| Copilot (AI) | No | Yes, with usage limits |
| Business use | Depending on the edition (Pro Plus: yes) | Intended for personal use |
In support, the most common confusion comes from the Microsoft account: many customers think Office 2021 needs a subscription because they are asked to sign in. It does not. Signing in links the licence to the account so you can reinstall it later; it does not bill you for anything.
How much does Microsoft 365 cost over several years?
This is the calculation to make before choosing. Microsoft 365 Personal (one person) and Microsoft 365 Family (up to six people) are paid monthly or annually; current pricing is shown on the Microsoft 365 plan comparison page. Prices went up in early 2025 when Copilot was added, and may change again.
The reasoning to keep in mind is simple: the subscription is paid again every year, for the whole life of the PC. Over three to five years, the total of the renewals generally exceeds the cost of a perpetual licence, especially if you use neither the cloud storage nor Copilot.
A perpetual Office 2021 or Office 2024 licence is paid once, and the PC using it five years from now will not have cost you anything more. That is why most of our home and freelance customers, who use Office on one or two desktop PCs, choose a perpetual licence. Conversely, a family of four who want Office on every computer, tablet and phone, with shared storage, often get good value from Microsoft 365 Family.
Which applications are included in each option?
The contents vary by edition, and that is often where the choice is made:
- Office Home & Student 2021: Word, Excel, PowerPoint (no Outlook), non-commercial use;
- Office Home & Business 2021: the same plus Outlook, commercial use permitted, available on Windows and Mac;
- Office Professional Plus 2021: Word, Excel, PowerPoint, Outlook, OneNote, Access and Publisher, on Windows;
- Microsoft 365 Personal or Family: Word, Excel, PowerPoint, Outlook, OneNote, Access (PC only), plus Microsoft Defender and Copilot in the apps.
One detail matters a lot this autumn: Publisher was removed from Microsoft 365 in early October 2026. Users with brochures, cards or newsletters in .pub format can no longer open them with a subscription. With an Office 2021 Professional Plus licence, Publisher stays installed and usable, even now that support has ended. Office 2024 does not include it either.
What happens if you stop paying for Microsoft 365?
When the subscription expires, the applications switch to “reduced functionality” mode: you can open, read and print your documents, but you can no longer edit them or create new ones. OneDrive storage reverts to the free plan; if you are over the limit, you can no longer add files, and Microsoft may eventually delete the excess content.
With Office 2021, nothing like that happens: the licence stays active with no time limit. It is an argument we often hear from customers who want a tool that simply works, with no deadline to keep an eye on.
If you are leaving Microsoft 365 for a perpetual licence, follow this order:
- Bring your important OneDrive files back to your local drive if you are over the free 5 GB.
- Uninstall Microsoft 365 via Settings > Apps > Installed apps.
- Restart, then install Office 2021 by following our guide to download, install and activate Office 2021 Pro Plus.
- Activate with your product key in File > Account, then check that “Product Activated” is shown.
- Cancel the subscription's automatic renewal in your Microsoft account, under “Services & subscriptions”.
Is Office 2021 still a good choice now?
Office 2021 has not been supported since 13 October 2026: it no longer receives security fixes, as stated on the Office 2021 lifecycle page. The applications nevertheless keep working normally, and the licence remains valid. We have set out what has changed in our article on the end of support for Office 2021 and your options.
In practice, Office 2021 remains relevant in three cases: you need Publisher, you are equipping a low-exposure PC (offline office work, workshop PC, till), or you want the cheapest perpetual licence for simple use. For a main PC that receives attachments every day and that you plan to keep for several years, we recommend Office 2024 Professional Plus instead, which keeps the same one-off purchase model with security updates until October 2029.
Office 2021 or Microsoft 365: which option for which user?
Here is the checklist we use when a customer asks for advice:
- A single PC, standard office use: perpetual licence (Office 2024, or Office 2021 on a tight budget or if you need Publisher).
- Several PCs in a household or small business: a multi-PC licence such as Office 2021 Pro Plus for 3 PCs avoids stacking up subscriptions.
- A Mac: Office Home & Business for Mac as a perpetual licence, or Microsoft 365 if you switch between Mac and PC.
- Working on smartphone and tablet, real-time sharing: Microsoft 365, whose full mobile apps and co-authoring are its real strength.
- Heavy use of Copilot: Microsoft 365, the only option that builds it into the desktop apps.
- Businesses using Teams, SharePoint and Exchange Online: Microsoft 365 Business plans, designed for that use.
Finally, note that Microsoft 365 Personal and Family are intended for personal use. A tradesperson or small business that invoices with Excel and Outlook should choose an edition that permits commercial use: Home & Business, Professional Plus, or a Microsoft 365 Business plan.
Frequently asked questions
Does Office 2021 require a subscription?
No. Office 2021 is a perpetual licence paid for once. Any Microsoft account you are asked for is only used to link the licence for future reinstallation.
Can Office 2021 and Microsoft 365 be installed on the same PC?
It is not recommended. Both use Click-to-Run technology and conflict with each other. Uninstall one before installing the other.
Do my Office 2021 documents open in Microsoft 365?
Yes, the formats are identical (.docx, .xlsx, .pptx). You can switch from one to the other without converting anything.
Is Microsoft 365 more secure than Office 2021?
Since 13 October 2026, yes: Microsoft 365 receives fixes continuously, while Office 2021 no longer does. Office 2024, also perpetual, is patched until October 2029.
Is there a free version of Office?
Yes, Word, Excel and PowerPoint for the web are free in the browser with a Microsoft account, but they have fewer features than the desktop versions and need an internet connection.
Making the right choice for your use
If you want a suite you pay for once that works with no deadline, a perpetual licence remains the most cost-effective option: compare the editions in our Microsoft Office collection, from the 2021 version to Office 2024. If you are still torn between perpetual and subscription, write to our support team with your devices and must-have applications: we will point you to the right option.