The activation of the Office 365 should not be tied to operating system, as long as software works there should be no problem re-activating Office 365.
Have you tried activating it again?
Activate Windows 7/8/8.1/10 with product key
The activation of the Office 365 should not be tied to operating system, as long as software works there should be no problem re-activating Office 365.
Have you tried activating it again?