Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello, thank you for reaching out to Microsoft Q&A.
Do you see your Office 365 Subscription under your Microsoft account here on this page?
https://account.microsoft.com/services
If the subscription is active under your account, please let us know the error message you receive when trying to activate it on the Office desktop applications.
You can try signing out of the app and signing in again.
(or) Try repairing office applications once, and then sign in again to register your license.
See if it helps.