DVD Audio Extractor version 6.0.0 and later require a new license file to work. If you purchased DVD Audio Extractor before May 31st, 2011, you'll need to sign up for a new account at our website and download license file within there. See details about how to upgrade your license at the tutorial http://www.dvdae.com/dvdae/tutorial/upgrade.
If you are already using 6.0.0 or later, simply install the new version over the old one.