How to Reinstall Windows 8.1 Product Key and Activation

ASUS X555LN (preinstalled with Windows 8.1), I actually forgot to make an image backup of the OS partition. Worse, I didn’t want to go through another episode of opening the laptop since it was one heck of a job and the unit’s still brand new. So here’s a hack I did to install a clean Windows 8.1 OS with the product key and of course activated.

  • Download this tool from NirSoft hat tip to Nir Sofer, you are one awesome dude =)
  • Attach the original HDD via USB. This now acts as an external drive, don’t boot to this hard disk it won’t work.
  • Important, run produkey as Administrator, otherwise the software won’t be able to see the key on the external drive.
  • Produkey will provide the product key (make sure to save this) and the Windows OS installed on the HDD. Mine was Windows 8.1 64bit single language.
  • Download the correct Windows iso and create a bootable usb drive from it. You can do it manually or just use Rufus to save time.
  • Install Windows with your key.
  • Boot and run CMD as Administrator.
    reinstall win8 key and activation
  • Then run this command slmgr -upk, you should get an “Uninstalled product key successfully” message.
    running slmgr -upk
  • Reboot and done. Product key restored and Windows is activated.
PLEASE NOTE, I have no idea on the legal implications of doing it this way but the bottom line is, I have a legal product key and used it only on the same computer where it’s intended. Moreover, this will likely work only on systems that came preinstalled with a Windows operating system. As usual, there are no guarantees in life, follow instructions at your own risk.  ]]>