A new window will pop up. Type your new 25-character product key into the boxes. The product key format is five groups of five characters (e.g., XXXXX-XXXXX-XXXXX-XXXXX-XXXXX). You do not need to type the hyphens; Windows will insert them automatically.

Click on the link that says Change product key (you may also see "Product key" or "Activation" depending on your system’s status).

Right-click on cmd.exe in the search results and select Run as administrator . Click Yes on the User Account Control prompt.