For a simple premium model with a 30-day free trial, you've got two reasons not to ask for the CC info until you're going to cut off someone's access to the pre

For a simple premium model with a 30-day free trial, you've got two reasons not to ask for the CC info until you're going to cut off someone's access to the premium product (you want to maximize the number of prospects, especially as a new entrant). I'd just make sure that you just "locked" someone's premium features/data if their credit card lapsed (if you're doing subscriptions) or if they decline to re-up (if you're allowing month-by-month PAYGO payments) - i.e. don't delete it accidentally when you downgrade an account. And even if you decide to follow 37signals w/r/t the premium version (ask at the time someone upgrades/purchases, but only but actually charge the card at the end of the first period), there's no reason to ask for a CC for the free version; you're making your sales funnel unnecessarily narrow. You can nudge/bother them to upgrade only when they're already customers. [I guarantee that no one has a more convoluted billing system than does Dawdle, so I've spent a lot of time dealing with this living hell. While we don't require up-front payment, we use credit cards for authentication as a fraud prevention measure for both creating (free) listings and for our "name your own price" StandingOffers. (I mean, if you're going to name your own price, and we want to charge you automatically when your StandingOffer matches a listing, we kinda sorta need your info up front.) Of course, the authentication charges are 1) expensive and 2) piss off customers, but what are you gonna do?]