Can someone point me in the right direction

[Clas]

Hi, long time member. Hope someone can help with a question. I am a long time Win7Pro user and perfectly happy with it. I want a spare pc as i do a lot and with an older Dell optiplex you never know if something will break. I bought another Dell with a fresh copy of the same OS, Win7 Pro installed. My question is this: if i clone the original pc to a ssd, and put that into the new pc...fire up, it will probably say i cannot use this key...so at that point what can i do to change that key to the correct one on the new pc. not trying to do anything illegal, just trying to save me a lot of effort installing programs and all the tons of settings i have gotten just the way i want them over the years. Hope someone can help....thanks, Clas