Why is Microsoft word asking me now for a product key. I never had one

A paid Microsoft 365 subscription normally activates Word through the Microsoft account used to purchase it, so sign in with that account instead of entering a product key.^1^

Reactivate Word

1. Open the Microsoft account Services & subscriptions page.
2. Sign in using the email address used to pay for Microsoft 365.
3. Confirm that Microsoft 365 appears and that its subscription status is active.
4. Open Word and select File > Account.
5. Sign out of any account shown there, close Word, and restart the computer.
6. Open Word again and choose Sign in, using the same account under which the active subscription appeared.

Do not buy another key. Microsoft 365 subscriptions generally do not provide or require a product key; the purchasing account takes its place for activation and reinstallation.^1^

If the subscription is missing or expired

• Missing: Try any other personal email address that may have been used for the purchase. Word cannot activate if the signed-in account has no Office product associated with it.
• Expired or cancelled: Select the subscription’s renewal or billing option on the Services & subscriptions page.
• Active but Word still requests a key: In Windows, open Control Panel > Programs > Programs and Features and search for Office. If multiple Office versions appear, uninstall versions you no longer use, restart the computer, and sign in to Word again. Multiple installations can create activation conflicts.^2^
• If activation still fails on Windows 10 or later, run the Microsoft 365 activation troubleshooter from Microsoft’s activation-error page.^2^

A product key is relevant only in specific cases, such as a new unused key card, certain one-time Office purchases, or qualifying workplace/volume-license editions. If none applies, do not enter a key obtained from another person or an online seller.

If the subscription is active under the correct account but activation still fails after the troubleshooter, use Microsoft’s public support page for account and activation assistance.^3^

References

1. Using product keys with Microsoft 365 | Microsoft Support
2. Unlicensed Product and activation errors in Office | Microsoft Support
3. Where to enter your Office product key | Microsoft Support