Or maybe, MrVang3034, Microsoft should never have given the upgrade for free at all.
The free Windows 10 upgrade is only good on the computer you upgraded. It is good for the life of the computer (motherboard), but only on that computer. You have to buy a retail copy of Windows 10 to have transfer rights.
The free Windows 10 upgrade does not use a product key. The computer is activated for Windows 10 (Home or Pro) by digital entitlement, a new way of activation. It is the computer that is activated now, not the software. That's why you can't transfer the free software. It is just like the copy of Windows that you get pre-installed on a new computer by the manufacturer. You can't transfer that Windows license either.
If you want Windows that you can tranfer to another computer, you can get it, but not for free.
Notice how often I used the words "free" and "upgrade" in this post? Its the key to understanding the Get Windows 10 program. It is a free upgrade. The Get Windows 10 program is not a free copy of Windows, it is a free upgrade of the Windows you already have.
I just found an instance where the Windows 7 product key was required for activation.
My wife has a Dell Inspiron 1545 notebook computer that had Windows 7 Home Premium. I upgraded it to Windows 10 - 10240 in July 2015 and it activated right away. I just got a good deal on a 120GB SSD drive and installed that in the old notebook, replacing the old spinning hard drive. Tried to do a clean install, skipping entering the key, and when Windows 10 - 10586 booted up it said it was not activated and wouldn't activate automatically.
So, I tried the new option of entering the Windows 7 Home Premium key that came with the notebook computer. In this case the Windows 7 key was printed on a label that is under the removable battery. It worked entering the Windows 7 Home Premium key and Windows 10 - 10586 activated instantly. I used the Settings, Activation, Change Product Key option to enter the Windows 7 Home Premium key.
So if a clean install of Windows 10 - 10586 doesn't activate automatically, try entering your old product key from Windows 7.
But this was the first time a clean install wouldn't activate automatically after it was installed. So I tried the option of entering the Windows 7 Home Premium product key to activate 10586. This worked perfectly. Went to Settings, Activation, Change Product Key and then entered the Windows 7 Home Premium product key that is on a label under the laptop battery.
I like to have the option to do a clean installation in case something went wrong and my computer became corrupt and I was not able to recover or revert back to the before setting. For those of us that did get the windows 10 0r 10 pro from the free windows 10 upgrade. MS should hold the product keys in they're server so that we can re-download the window 10 back into our system from the server and along with the product key should we decided to do a clean installation or transfer it onto our new computer should our old computer died. There should be a way for users to register they're ID onto MS server so we can be identify as the owner of that product key and be able to just re-download once we provide proof of our valid state ID and prevent the OS from being pirating or duplicating because it is already register under our personal information.
I mean this is like if I offered you a free steak dinner and you were complaining that I didn't toss a lobster tail on top of it.