My MS Word has worked fine until a few days ago, but suddenly it has decided Microsoft 365 needs to be activated and stopped working. Any idea why this happened and how to fix it? Many thanks.

Hello @Joyce Lee

What you're describing normally happens when Word can no longer verify the Microsoft 365/Office license. When activation fails, Office can enter reduced functionality mode, where documents can still be opened and printed, but editing features are disabled.

First, open Word and go to: File > Account

Please check what appears under Product Information and User Information. In particular, look for messages such as

Unlicensed Product, Activation Required, Subscription Expired, and Account Notice

Also check which Microsoft account is signed in to Word. If you have a Microsoft 365 subscription, it needs to be the account associated with that subscription.

Sign in to your Microsoft account and check Services & subscriptions to confirm that Microsoft 365 is still active:

A subscription can become inactive unexpectedly because of an expired or declined payment method, cancellation, or another subscription/account issue. Subscription and payment issues can cause these activation notices.

If the subscription shows as active, don't purchase another copy of Microsoft 365 yet. Try signing out of Word under File > Account, closing all Office applications, restarting the computer, reopening Word, and signing back in with the account that owns the license.

I recommend checking for multiple Office installations, since having more than one Office version installed can cause activation conflicts. You can check this under Control Panel > Programs > Programs and Features.

If everything looks correct but Word still says activation is required, run Microsoft's Microsoft 365 activation troubleshooter through the Get Help app. It can automatically diagnose subscription and activation problems.

Could you tell us exactly what Word shows under File > Account > Product Information, and whether your Microsoft 365 subscription shows as Active under Services & subscriptions?

If there's an activation error code, please include that as well. That should tell us whether this is a subscription/account issue, an activation-token problem, or a different Office license.

References:

Unlicensed Product and activation errors in Office

Microsoft 365 subscription notices explained

Activate Office for Windows

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