Difference between Freeware and Registered versions
AXS is generally a free product and nobody is required to pay any money to use it.
If you decide that you want to remove the publicly viewable copyright notice - the part that says "AXS Script Set Version 2.3.0.XXXX is copyright 1997-2001 by Fluid Dynamics" at the bottom of the admin page - then you may purchase a $20 "Copyright Suppression License". This does not transfer the copyright to you, but it allows you to remove it so that your clients aren't distracted by it, or whatever.
Copyright suppression licenses may be purchased at http://www.xav.com/scripts/axs/purchase.html.
"Difference between Freeware and Registered versions" http://www.xav.com/scripts/axs/help/1007.html