This article explains how to Fix the "Windows 8 activation problem with Error Code 0XC004F074"
You may encounter an error message "Error Code: 0xC004F074" when trying to activate Windows 8 with the 25 digit product key. To resolve the issue follow the below steps:
Go to the run command by pressing Windows key + R and type "cmd"
Now in the command prompt type "slmgr.vbs -ipk xxxxx-xxxxx-(25 digit product key) and press Enter.
After that type slmgr.vbs -ato and Enter.
If you still get the error , open the command prompt again and type "Slui 3" and enter your 25 digit product key in the popped out Window.
Click Activate and open cmd in Administrator mode (right click cmd -> Run as Administrator) and run the command as "sfc /scannow" then press Enter.
Restart your computer and activate Windows 8 again which will work perfectly.
Alternatively, you can also download the Microsoft Hotfix for Key Management Service (KMS).