Changing product key after Installing Windows 8
At the administrator command prompt, type in "slmgr.vbs -ipk " slmgr.vbs -ipk 00000-00000-00000-00000-00000 To activate windows after changing the key, run "slmgr.vbs -ato" More details in the following link: http://tweaks.com/windows/39026/change-windows-product-key-after-install/