Product Key

Could someone please tell me if you can find the product key on a Win98 Cd, if you have lost the registration label with the identification code on it. I am sure that I seen somewhere on
Tech Republic Q&A that you can go to Find and type in something like CD Key, I have tried this but does not work. Any ideas I have a ladies computer that I had to format, she has her Win98 Cd but not the Key. Thank you