Aperture Software

Have a look at this support article:

Troubleshooting Professional Application Serial Numbers

Make sure you do not mix up look-alike letters, like 0 and 0, or 1 and I.

Don't enter the the numbers from the numerical pad.

Is your Aperture 2 version an upgrade from version1? Then you may need also to enter the Aperture 1 serial.

Regards

Léonie

The serial number is accurate (checked several times), but it is still not recognized.

Does Aperture give an error message - serial number invalid? Or does it simply prompt over and over again for the serial number?

Did you enter the serial number from an admin account?

I have Aperture, version 2.1.4. I migrated data from my old iMac to a brand new Mac Pro.

Try to reinstall Aperture from your original disks. Pro Applications do not migrate well. If that does not sove it, contact Apple for a replacement serial number, see:

Apple - Support - Pro Applications - Serial Numbers

Use your Support ID as proof of purchase.

But better do not post the ID here, this is a public forum.

Léonie