Run the following command in Command Prompt
c:\windows\system32\slmgr.vbs /ipk [product key]
Replace the [product key] including brackets, with your product key — you can use dashes.
Run the following command in Command Prompt
c:\windows\system32\slmgr.vbs /ipk [product key]
Replace the [product key] including brackets, with your product key — you can use dashes.