Where Do You Put The Key Generator I Reinstalled Vista On My Laptop And Now It Says The Key Is Invalid?

I reinstalled Vista on my laptop and now it says the key is invalid? - where do you put the key generator

I bought me a laptop that was in 2007 loaded with Windows Vista had the product key for a small label on the bottom of the laptop, as do most teams. Anyway, I went straight to my team, but I've forgotten where I am from ... I have to reinstall Vista (which completely erased my hard drive if the old files, it is not necessary) and I could not see the button, I found this program you can download that actually get into Vista and found that (the product key is not a public key generator.) worked for a while, and everything was fine, but now when I get Vista this window with several options, one of the Enter a new code from Microsoft to ask for help, and it is access to a computer with reduced functionality (which is what I amdoing now) .. I refuse to buy another product key, since this is the copy of my sight .. Help?