I'm pretty much OK with saying "Give us your credit card number; we'll charge you after your free trial" and then saying "Your free trial expires three days from now." People are easy to nudge into desired behaviors: they find it easier to go through with a decision they have already made than to make what seems like a separate decision at the 30 day point. I know of no moral stricture which says I should choose the sucky-to-the-business model just because it is sucky-to-the-business.