Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
What are you using it on, Windows 11, or MacOS?
Did you purchase directly from Microsoft, or from Apple App Store, for example? Please let me know because the installation method can be different in order for the account to be recognized.
In the apps, can you make sure you are signing in with the right account - check the user icon on the upper right.
If you got it from Microsoft, check https://account.live.com > Subscription, confirm that the name is indeed Microsoft 365 Personal and it is active.