Please keep in mind that you only have access to this Office 365 Offer as long as you are a student at your School or University.
This can have multiple different reasons:
1. Your Office 365 Product has expired and is not any more licensed. You can check this by opening this URL in your Browser “https://portal.office.com/account/?ref=MeControl” and Sign-in with your Account that where you have the Office 365 Licence attached.
When Sign-in, you should see the page My Account. On this page, you should see a Tile with the Name Subscriptions. Please click on the view Subscriptions Button.
This should get you to this view, and you should see a Licence similar like in the screenshot. If that’s not the case, your account does not have any more a licence attached to it. Please contact your O365 Admin or Support.
2. You have renewed your Licence by purchasing a new O365 Product in the Shop. But you still have the message that your account is no longer active.
Try to sign out of all your Applications. Then Sign in again. Check if that solves the problem. When the problem persists, please contact Support.