HELP! Windows 8.1

[Solitude]

So i have built a pc for a friend of mine and it works fine, BUT... We forgot to buy an optical drive luckily i had a copy of windows 8.1 on my hardrive (illegal). However we have bought a legit copy of windows, now what i need to know is how do i change the pirated copy into the legal one. Ps he needed to have the computer running hence why i put the illegal version on. I need a full guide please.

[LinusFTW]

I dont know

[William12h]

Just download the Windows 8.1 checker thing and Download it then install it to a USB (They call it a media device) Then plug the USB into his PC and boot from it. You will need the Product key on hand to download the OS and install it.

 

http://windows.microsoft.com/en-GB/windows-8/create-reset-refresh-media

 

http://go.microsoft.com/fwlink/p/?linkid=271128  <Link in Post above to the Windows 8.1 downloader.

 

So i have built a pc for a friend of mine and it works fine, BUT... We forgot to buy an optical drive luckily i had a copy of windows 8.1 on my hardrive (illegal). However we have bought a legit copy of windows, now what i need to know is how do i change the pirated copy into the legal one. Ps he needed to have the computer running hence why i put the illegal version on. I need a full guide please.