Pin #'s, Serial #'s, Program Keys and Program Codes??

Going thru my collection of software I have discovered that over several periods of moves, visitors, ugh!, and various other reasons - - Some of my programs are missing important documentation such as Serial #'s, Program Codes/Keys, and Product keys/codes. I was told that there were program(s) available online that can be downloaded to help me is this matter. I also have the problem of having purchased a new computer that has programs which are requiring one of the items I listed in order to activate them. Any suggestions??/