I've been using license files for my upcoming app, the bêta-testers love 'em. They say it's far better than having to copy long and boring keys. Oh, and you can store a whole lot of different information in it too. (I put in a expiry date field, so even tho the licenses i sell are for life, I can use limited licenses for events like MacHeist's freebies etc.)

Btw. I love your apps, sucks I don't have a use for it, tho.