For those who have a need to activate windows 2012 servers or later and/or clients with windows 8 and above it is well worth having a look at AD based activation.
There are a couple of prerequisites, notably that the AD schema must be extended to the 2012r2 level and the Volume Activation Services role (VAMT) must be installed on a 2012r2 server.
Once you have that you can add your KMS host key using VAMT – this key can be activated online or over the phone.
**When I last did this at a dark site I was able to use a smartphone to complete the activation rather than the rather tedious process of relaying seemingly endless amounts of numbers**
When this is complete qualifying client computers are activated from a Domain Controller during their startup process.
This removes the need to have KMS servers in your environment along with the minimum count requirements associated (the number of requests before the KMS server will activate clients).
You’ll still need KMS if you need to activate workgroup PCs or windows 7/2008r2 but for those migrating to Windows 10 and especially within a VDI deployment I think this is certainly the way to go!
Importantly you can also activate office 2013 suites and above this way.
For the full process check out the TechNet article here