Hey so after doing research i have one question from which ill quote
"To take advantage of your Windows 8 Pro downgrade rights, you need installation media (such as DVD or USB key) for Windows 7 Professional or Windows Vista Business. You also need a valid product key for the older OS. Microsoft says it's fine to use a product key currently in use on another machine; you just need the old code to get past the product key request during installation."
Okay, "Its fine to use a product key in use". So... say i have one from windows 7 pro
And i start a home service to downgrade from 8
I use the same product key to downgrade on multiple laptops, any issue with this?