Let the user win in the normal case. If they pay for the smaller plan, and the next day they upgrade, they'll happily receive the larger plan until the next bi

Let the user win in the normal case. If they pay for the smaller plan, and the next day they upgrade, they'll happily receive the larger plan until the next billing cycle. This also means they can cheat the system by paying, the next day upgrading, then downgrading right before the next billing cycle. Oh well, we've got bigger fish to fry. If they love your service enough to live with the pain of having to time their upgrades and downgrades, you have a gold mine in your hands and you're probably not hurting from being unable to collect your $34. As for the downgrade case, the TOS applies in this case. Fortunately, very rarely do our customers downgrade. After all, we've built a service that helps them build their company (and I gather jMockups is much the same). It hurts us more than just financially to see them shrink in size. At the end of the day, we're running on a streamlined billing system that doesn't take more than a paragraph to explain. And this helps because we also put up an explanation right on the account upgrade page. More importantly, we're not wrestling with unmanageable amounts of code or fretting about a third party vendor meeting business needs - more time to spend improving the product in more important ways.