I'm using a KMS activated version of Win 8 Pro which was a clean install. I'd like to go legit and buy a $39.99 key from Microsoft. Will I be able to just add this key and re-activate or would I have to re-install Win 8? Thanks in advance.
Just install your key using the Activation Center, activate and done. When the edition match, the OS will install and activate automatically the product key online.
If you'd like to go legit by cleaning all traces of KMS first, you can do the following, in this order: 1. run "slmgr /ckms" to remove KMS server settings 2. run "slmgr -cpky" to remove the KMS key from your system 3. run "net stop sppsvc" to stop the activation related services 4. delete "C:\Windows\System32\spp\store" folder and everything in it 5. run "net start sppsvc" to restart the service By doing this you'll end up with the watermark again, and will be warned to activate. Just enter your legit CD-Key and your install will be as good as it gets.