Credit problem

I don't get it, so we have a 100 credit. And if we don't use it, we still have 100 credit is it not sum with tomorrow, and create sometime like 200. So, if I don't spend it today, my 100 will remind for tomorrow, But if I use it, it will recharge to 100 again. Are you sure? so i never would seen 200 or anything higher, there is no enjoying time to use a lot coin at one