To Reset the Office 2016 Keys, including Project

GET LAST PART OF OLD KEY

c:

cd "C:\Program Files (x86)\Microsoft Office\Office16"

cscript ospp.vbs /dstatus

pause

Then login at office.com/account and see which key got used

UNREGISTER OLD KEY

c:

cd "C:\Program Files (x86)\Microsoft Office\Office16"

cscript ospp.vbs /unpkey:RX83M

pause

REGISTER NEW KEY

c:

cd "C:\Program Files (x86)\Microsoft Office\Office16"

cscript ospp.vbs /inpkey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX

pause

Finally, run and activate.

 - - -

references

example
rem cscript.vbs /unpkey:___

other notes
https://www.apeswithcomputers.com/article/use-cscript-to-activate-office-2010-2013-2016
To view the installed product key, execute cscript ospp.vbs /dstatus
To uninstall an installed product key, execute cscript ospp.vbs /unpkey:XXXXX
Replace the XXXXX with the last five character of the currently installed product key (found in step 3).
To install a new product key, execute cscript ospp.vbs /inpkey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
Replace the XXXX with your full product key of Office.
To activate Office with the new product key, execute cscript ospp.vbs /act
Restart the Office application and Office will be activated.

and
More steps from here
https://blogs.technet.microsoft.com/odsupport/2015/05/01/how-to-reset-an-office-365-install-to-the-initial-activationinstall-state/


also, to replace key
gui or cl
http://www.intowindows.com/how-to-properly-change-product-key-of-office-2013/