Windows 10: Don't know which Windows 7 Product Key has been used

I am planning a clean install on a new SSD. I've read that I have until December 31 to do the upgrade.
I have used the media creation tool to create a disk.
My problem is that I have a half-dozen windows 7 Home Premium boxes and don't know which ones have been used and which ones haven't been used.
What if I enter the product key and it is one that has been used. Can I assume that I will I be given a chance to try a different one?

(Just planning ahead--I can't just do it right now since the computer is at a different location.)

:)

 

Can I use my product key of window 8.1 to active windows 10 when re-installing my computer?

Today I have upgraded my computer from windows 8.1 to windows 10. For now, the OS has been activated but I don't know the product key of my new OS. What if my computer has any problems and I want to re-install it.

Which product key can I use to keep my genuine windows 10?

 

Upgrade to Windows 10 from Windows 8.1 causes 0xC1900101-0x30018 error and reverts to 8.1

I was told to reinstall Windows 7, then upgrade. I have purchased a product key, and downloaded Windows 7 Pro, which came with a 32-bit and a 64-bit. I burned them to disk, but mistakenly installed, after formatting the hard drive, with the 32-bit disk.
It took the product key, but now I need to actually install the right version for my 64-bit machine, and the product key has been used, mistakenly. The ONLY way I got past all the problems was to wipe everything off, and do a clean install, but this mistake
has nullified my purchase of a product key. If there is a private email from which the tech who reads this could send me an email, I will provide the product key I need to be reset, so I can install the 64-bit version of Windows 7 Pro. My intention, having
bought both a Windows 8 Pro Upgrade (that product key is now "blocked") AND Windows 7 Pro with a new product key, is to get a good installation of either Windows 7 Pro OR Windows 8.1 Pro, so I can upgrade to Windows 10. Either the unblocking of the Windows
8.1 Pro key, OR the resetting of the Windows 7 Pro key, would work for me. Until then, this has taken up days of precious time, and the product key server has not been kind to me... ;-)

 

Yes, you can try as many keys as you want - just make sure you have Win 10 Home installed.