Although this may seem obvious to some, I always wondered how developers intended to generate revenue from a normally paid app going free. As Paul Mayne, founder of Day One, explains, increased brand awareness should increase the chance of an effective paid upgrade.

That paid upgrade, I assumed, was merely a way of generating enough cash to keep the lights on for another few years. But, by monetizing free users and by cashing in on customers for a second time, the paid upgrade is more than just a way to screw past customers.