There are times when you want to prevent others from using your Windows Product key on another or their personal computers. This is to prevent piracy of your legitimate windows license.
So here is the command that you can run from the CMD to remove the Windows Product key once you have activated the key. This will keep your activation information intact but will remove the product key so that no body else can use that.
1. Open the Command Prompt
2. Type Slmgr.vbs /cpky
You will get a message that the product key is removed from the registry, thus your windows license is safe.