Need to reinstall Adobe PSE 10 but don't have serial #.

It used to show up on my Adobe but it has dissapeared after I registered an old version of InDesign that I had lost years ago and didn't realize I could reinstall without the disc.  Now the only thing that shows up is InDesign (orginally registered in 2007).  I purchased PSE 10 physical discs so I don't have an email from Adobe with the registration #.  What happened and how do I find my serial # so I can reinstall?  I do have it installed on another computer so I still have access to the program on my laptop, so if there is a way to locate it within the program I can do that.