Another fairly easy way to do this kind of thing is to use the DYLD_INSERT_LIBRARIES variable. You can reverse engineer the classnames with class-dump, subclass a class and override a suitable function e.g. IsLicenseValid() to just return true; You can then start your program and insert your new subclassed class into it like this:
I didn't know about that, that's really neat! Will need to do some research into that!
PS: I'm poking fun at myself—since I wrote the original app, including misspelling. Also, I use American english, but I do prefer to use the british form of 'spelt' or 'burnt.'
$ DYLD_INSERT_LIBRARIES=/path/to/your/Subclassedlibrary.dylib arch -i386 /Applications/OriginalApp.app/Contents/MacOS/OriginalApp &
And on a sidenote, I thought it was funny to see him refer to something as 'badly spelt' - I thought that 'rye' remark was a bit 'corny' (rimshot :-)