Proposed explanation and solutions for Office C2R 'Your license isn't genuine' banner:


Solution (Known to be perfect):

Preparation:

Install any of the below products:

Activate with KMS:



Experimental solutions: 



The solutions which are currently working but won't work with upcoming updates:



The solutions which are not working for all:



The explanation on how Office is identifying non-genuine KMS license:

To be added...
 



P.S.

Updated on 23-May-2021