Step 1 - Launch cmd.exe in Administrator mode (right click on cmd.exe and select "Run as Administrator")
Step 2 - In the command window type slui.exe 3
Step 3 - In the new Window that pops up, enter your new licensed Windows 8 Enterprise Product Key
If you purchased a downloaded a licensed version of Windows Enterprise using your MSDN licensing then this option will work and your Windows will be activated and ready for use
ENJOY the most powerful OS built by Microsoft ever!