Windows 7: Use Windows 7 Product Key that has ran out of licenses

I am building a new computer (the one described below). I want to use a current Windows 7 Ultimate Product Key, however I have used it on 3 computers, and I have replaced those computers with Linux. Now I want to transfer Windows 7 to my new computer, but according to what I know from testing the product key, I can't transfer Windows 7 unless the other computers are still running windows 7 with that product key. Also, I'd prefer not to call Microsoft Customer Support if it isn't automated, as calling Customer Support can be awful because of the music and other stuff.

Thanks in advance

You can only use 1 retail key on 1 computer at a time.

And yes you`ll most likely have to make a phone call, there`s no way around that.