>that the billing and billing limits should also be able to respond similarly How so? With a pay-as-you-go system, firing off warnings and giving a projection

>that the billing and billing limits should also be able to respond similarly How so? With a pay-as-you-go system, firing off warnings and giving a projection of their future costs (which is hard when startups tend to have spikey traffic) is about as good as you can do. Edit: I should add that the common solution to controlling your billing in situations like this is having some overflow path built into your beta app ("Sorry, we're not taking new users at the moment" or the like).