trying to open an excel (aslo in word) file on mac. app doesnt recognise i have subscription

On macOS 12 or later, resolve the Office 0x0 / License Not Found activation issue by updating Word and Excel through the same installation source from which they were originally installed.^1^

Update Office

First, select Apple menu → About This Mac and check that the Mac is running macOS 12 or later.

If Office was installed from Microsoft:

1. Quit every Microsoft Office application.
2. Open Finder → Applications → Microsoft AutoUpdate.
3. If Microsoft AutoUpdate is not listed there:
   • In Finder, select Go → Go to Folder.
   • Enter /Library/Application Support/Microsoft/MAU2.0/.
   • Open Microsoft AutoUpdate from that folder.
4. Select Update All.
5. When updating finishes, reopen Word or Excel and test editing and saving.

If Word and Excel were installed from Apple’s App Store:

1. Quit all Office applications.
2. Open App Store → Updates.
3. Update Microsoft Word, Excel, and the other installed Office apps, or select Update All.
4. Reopen an Office application and test activation.

Microsoft lists this particular macOS 0x0 / License Not Found issue as resolved through the Office updates.^1^

If updating does not restore activation

Reset the locally stored Office licenses using Microsoft’s License Removal Tool. This removes Office licenses from the Mac, so have the subscription account and password available before proceeding.^2^

1. Quit all Office applications.
2. Download the Office License Removal Tool from the Microsoft Support page cited below.
3. Open the downloaded .pkg file.
   • If macOS reports an unidentified developer, Control-click → Open.
4. Select Continue, follow the prompts, and select Install. Enter the Mac administrator password if requested.
5. After the tool reports that licenses were removed, select Close.
6. Open Word or Excel and sign in with the account associated with the Microsoft 365 subscription.
7. If offered a choice between a one-time Office license and Microsoft 365, choose Microsoft 365.
8. After activation succeeds, restart the Mac.
9. Delete the license-removal installer from Finder → Downloads.

Editing successfully in the web apps does not by itself prove that the same account has a desktop-app license, because Office web access is available to Microsoft accounts without a paid desktop subscription. If activation still fails after the update and license reset, check the account’s Services & subscriptions page and confirm that Microsoft 365 is listed under the exact account being used in Word and Excel.

If the Mac is older than macOS 12, the documented 0x0 update resolution is not applicable; upgrade macOS first if the hardware supports it.^1^

References

1. Unknown Error 0x0 or License not found error in Microsoft 365 or Office running on macOS | Microsoft Support
2. How to remove Office license files on a Mac | Microsoft Support