If you purchased Microsoft 365 directly form Microsoft, log into your Microsoft account on this ink and check if you can see your Microsoft 365 subscription listed there and if the expiry date on the subscription correctly indicated the expiry date for the new subscription.
https://account.microsoft.com/services/
If that is correctly indicated on your account online, if you have Office already installed on your PC, at the top right of Word, log out of Office then restart (not shut down) your PC and log back into Office to check if your subscription is then correctly registered in Office.