So I got tired of dealing with my old computer and a friend of mine had a used computer from his job they were getting rid of. It's a Dell Optiplex 7010 and it didn't have anything wrong with it with the exception of Windows 10 and I'm not ready for Windows 10. I upgraded the BOOT Drive to a 500 GB Samsung 860 Evo SSD and PUT in 16 gigs of G skill 1600 memory along with my 4 terabyte HARD drive for storage. I installed Windows 7 Professional as per the label that was on the computer itself and tried using the 25 character key from that label but it won't work so I was wondering if I'm supposed to use a specific build of Windows 7 Professional or does it have to be one that's downloaded specifically from Microsoft. I was under the assumption I could throw any Windows 7 Pro on there and be able to use the CD key from the label. Any help would be appreciated in figuring this out OTHERWISE I'd have to call Dell and BUY their restore flash drive and I'd rather not if I don't have to.

Thanks A Bunch
JohnHi John,
I suspect that your friend took advantage of the free upgrade to Win 10 from Win 7. If this is the case then by accepting the free upgrade this rendered the Win 7 Product Key unusable.
You can download for free the original version of Windows 7 from here.

https://www.dell.com/support/article/en-si/sln299044/how-to-download-and-use-the-dell-os-recovery-image-in-microsoft-windows?lang=en

It will make a recovery pen drive with the version of windows the computer was supplied with.He will still need a valid key...I'll give it a shot and see if it works. If anyone else knows of something different I'm all ears.

Thanks again for your help, John