Unless you register AVSAudioEditor the program will have limited functional features. It will not allow you to save files.
You can register AVSAudioEditor online using credit card: http://www.avsmedia.com/AudioEditor/buy.aspx
After purchasing AVSAudioEditor you will get a Registration Name and Serial Number. Once you start to run the program go to Menu/Help/About pull-down menu.
There press Registration button and enter your registration key.