There's readable and then there's readable. For example, compiled C programs are extremely difficult to decompile - generally if you're going to do that your time would be better spent reimplementing it yourself. But Perl is different. PerlAPP, Perl2EXE and PAR all function, albeit in slightly different ways, by bundling the Perl interpreter and your Perl source code into a single .exe file. This means that with only a moderate amount of work, someone can pick apart that exe and extract the original source - it's not even decompiling at all really. Bearing that in mind, I wholeheartedly agree with the suggestion that what you really need is a solid licensing agreement.