Recently, I ran into a support issue were a IT support technician upgraded a device to Windows 10 and installed Microsoft Office 2016 ProPlus, and every time an Office application opened an Office 365 activation window would appear.
The device is domain connected and the Microsoft Office ProPlus is volume licensed, so Microsoft Office should not be prompting for activation.
My first thought at a solution was to simply run the the volume activation manually through the command line. If you are unfamiliar with activating Office through the command line the below shows how to manually activate Microsoft Office:
Installs a product key (replaces existing key) with a user-provided product key.
Activates installed Office 2016 product keys.
However, after running the above the activation would fail.
After the above failed I checked to ensure the installed office produce was in-fact active by opening an office application, going to the File tab > Account to view the current activation status of the Office product. Office showed as active.
Lastly, I figured this consistent prompt probably had to be a Windows registry setting, so I began reviewing the window registry and this is what I found.
Here is the registry key that needs to be deleted to remove the consistent prompts to activate the Microsoft Office application.
You can manually delete by navigating to the OEM key and deleting the enter.
Or you through a script / command line by running the following.