justperso
What version of Premiere Elements do you have and what computer system is involved?
I have Premiere Elements in the box packaging for versions 4 through 12, so once you supply the information requested, I will give you exact details on where to find the serial number.
Here is a link to give you the general idea
https://helpx.adobe.com/x-productkb/global/find-serial-number.html
ATR