If you have access to a VLSC and can get KMS licenses, you may see keys for different Operating systems.  Intuitively, that suggests you would register each key to be able to activate a corresponding operating system.  Not so.  Get the highest level operating system KMS and subsequent operating systems are covered by the one key.  For example, Windows 2016 covers 2012, 2008, 10, and so on…

Check out this article for more detail: Windows Server 2016 Activation

Office 2016 KMS license in Windows 2012 is a bit goofy.  Intuitively, you’d think you would use the Volume Activation Tools to plug in your key.  Nope.

Download and run the Microsoft Office 2016 Volume License Pack.  It will launch the VAT GUI and then you can plug in your KMS license.

Why is it done that way?  I honestly don’t know.  I’m sure there’s a Microsoft explanation why but I don’t feel like digging through the Internet to find an obscure article with an unofficial explanation.  I’m just glad I finally got the KMS license thing set up.