Having to Reactivate Office 365 application License every day after 25 hours on a Mac Pro.

Since Office for the web works and the Mac apps lose activation daily, the most relevant supported fix is to fully clear the local Office activation state and reactivate.

1. Quit all Office apps.
2. Run the License Removal Tool to remove existing Office license files on the Mac.
3. Open Spotlight Search and open Keychain Access.
4. Delete these entries if present:
   • Microsoft Office Identities Cache 3
   • Microsoft Office Identities Settings 3
   • Microsoft Office Ticket Cache
5. Restart the Mac.
6. Open any Microsoft 365 app and sign in again with the school account that has the active license.

Additional checks that are directly relevant:

• Verify the Mac can reach the internet consistently. Microsoft 365 for Mac must contact the Office Licensing Service online to keep activation valid.
• Confirm the school account is the same account being used to activate Office. If the wrong account is signed in, Office can show No license found.
• If the school account license was not set up correctly, the organization’s IT administrator needs to verify that the Microsoft 365 license is assigned to that user.

Important notes:

• Changes in Keychain Access require local admin privileges.
• If the Mac cannot contact the Office Licensing Service, Office can fall into reduced functionality mode.
• For organization-managed Microsoft 365 on Mac, users activate by signing in themselves; activation is tied to the licensed user account.

• What to try if you can't install or activate Office for Mac
• What to try if you can't install or activate Office for Mac
• Overview of activation for Office for Mac