How do I now put it on another computer? I only have the license/reg number that is on the software. I'd appreciate whatever help anyone has to give!
You can still download the Aperture 3.1 Trial installer to reinstall Aperture from this webpage - there is a link to the trial and instructions on how to reinstall - don't let the title of this page distract you :
The Aperture 3 serial number will be available in the about panel, when you are running Aperture on your old mac (from the main menu bar: Aperture > About Aperture).