If you want to enter a different serial number for Aperture follow these steps.
Delete your ProAppsSystemID file
1) Delete your copy of the Aperture in your Applications folder manually
2) Make sure you have your serial number in hand for reference to re-serailize
3) Delete your ProAppsSystemID file in Library/Applications Support/ProApps folder
4) If you don’t care about preferences and metadata presets you can delete those as well for a clean install. It should, however, be ok to leave them from the previous version you were running.
5) Re-launch Aperture. Once you’ve done that, you should see you are running Aperture 3.0.1 and that it is not referenced as a trial in the Aperture menu.
this is great if you want to extend your trial another 30 days
