when you open Word, Excel, or any other Office application if you see a notice to buy, renew, or reactivate your Office 365 subscription , you’ll need to take action in order to keep using Office.
Check Some Error messages & their solutions here :
Renew your subscription to Office 365 by doing one of the following:
- If you see RENEW YOUR SUBSCRIPTION in the yellow warning bar, select Buy, and follow the steps to renew your subscription online.
- If you see SUBSCRIPTION EXPIRED in the yellow warning bar, select Reactivate, and then select Buy to renew Office online. If you bought a new, unused Office 365 product key from a retailer, select Enter Key.
If there are still Office installs available, you can select Sign in and enter your Office 365 account.
This will add the device to back your Office 365 subscription.
If there are no Office installs left, you can deactivate an existing Office install using the steps in Deactivate an Office 365 install.
For more details, visit : www.office.com/setup