Bios product key

[Shinascus]

Hello,

I am having some problems with computers here at work.

Some PC's had issues with the motherboards.
These have to be swapped.
Now the vendor we buy them from tells us that we have to ship the entire PC. So they can remove the Windows 8 Product key from the bios. And implement it in the new motherboard.

Obviously we don't want to take the computer from a customer who just bought it, we need a quick fix.

I hope someone can help me out and teach me if there are methods to remove/modify/inject these keys into the Bios.
Manual or by a created tool.

I really hope to hear from you.

Thanks in advance!