From the website:
Caution
When you activate Windows or Windows Server with a KMS host, the keys provided here are intended for volume licensing scenarios and can’t be used with retail editions. KMS client keys won’t activate or serve as a retail license key. If you installed a retail copy of Windows, you must use another activation method, like a MAK or by purchasing a genuine retail license. To learn more, see:
So not really a solution for the average person, if I understand this correctly.