You could cripple important functionality (like the final step in processing an order) and email the few remaining lines of critical code in a standalone .pm to users who pay.

You could sell a service. Bloggers can download a multitude of software but many pay a monthly fee for the simplicity of click-and-go blog web sites. Like the support services suggested in other posts, hosting services can be tacked on to just about any software business model.

You could use google to find unregistered users running your software and send your accountant and lawyer after them. If the user circumvented the register.pm mechanism above, then tack on a DCMA bonus.

You could sell auxilliary services besides support. Coordinate having your software suite's interface and documentation translated into different languages, and take a percentage.

You could put 'THIS SOFTWARE IS NOT LICENSED' across all of the graphics you supply and sell the replacement pack. Have lots of little graphics so that it would be tedious to replace every single one. This preserves all your functionality for demo purposes while limiting its commercial potential.

Failing all else, have your software email you any credit card numbers it receives.

Anonymous_Monk, please message me. I want to know more about this auction software.

update: mattr made all my points for me. never mind.

The largest peace protest in history is happening this weekend