You can stop the notifications by following steps
If you are looking notification messages are "Renew your subscription" or "Subscription expired"
Renew your subscription to Microsoft:
- If Renew your subscription appears in the yellow warning bars, click Buy to renew your subscription online.
- You can renew your Office online by selecting Buy to Reactivate Office Online if Subscription expires in the yellow warning bars. Enter Key if you purchased a Microsoft product key that is not in use from a retailer.
Close all Office applications after you have renewed your subscription. This will remove the renewal message. For assistance renewing your subscription, visit Microsoft Office Subscription Expired.