Getting message: Detecting a one-time purchase license

The message appears because Office for Mac was installed from the Mac App Store, but the license is a one-time (perpetual) Office 2021 license, which is not compatible with Mac App Store Office apps. To use the Office 2021 license again, the Mac App Store versions must be removed and the correct Microsoft-downloaded apps installed and activated.

Follow these steps on the Mac:

1. Remove the Mac App Store Office apps
   1. Quit Word, Excel, PowerPoint, and Outlook.
   2. Open Finder → Applications.
   3. Locate Microsoft Word, Microsoft Excel, Microsoft PowerPoint, and Microsoft Outlook.
   4. Control‑click each app and choose Move to Trash.
   5. Empty the Trash.
2. Remove any old license files (recommended)
   1. Download the license removal tool.
   2. Open the .pkg file from the Downloads folder.
   3. Select Continue and follow the wizard.
   4. When ready, select Install (enter the Mac admin password if prompted).
   5. After it completes, select Close.
3. Install Office for Mac directly from Microsoft Use one of these options:
   • If the Office 2021 product is in the Microsoft account, sign in at the Microsoft account dashboard and install Office from there; or
   • Download the Office 2021 for Mac installer directly:
     • Office 2021 for Mac Installer
   1. Open the downloaded installer package and complete the installation.
4. Activate with the Office 2021 license
   1. Open Word (or any Office app).
   2. Sign in with the Microsoft account associated with the Office 2021 purchase, or enter the product key if prompted.
   3. If asked to choose a license, select the perpetual/one-time Office 2021 license.

After activation, restart the Mac and reopen the Office apps; they should work without the “one-time purchase license” warning.

References:

• Microsoft Office activation and the Mac App Store
• How to remove Office license files on a Mac