Open Command Prompt as Administrator.
: The most reliable way is to enter a valid 25-character product key. You can find this in your confirmation email if you purchased a digital copy or on a sticker inside the Windows packaging.
No use activadores no oficiales. Para cumplimiento legal y seguridad, adquiera una licencia oficial o use alternativas legítimas.
Microsoft provides several legitimate ways to activate this version: Windows 8.1 pro build 9600 activation - Microsoft Q&A