You won't be able to tell with your MB, but you should be able to tell with your phone and your
MDE account. Unfortunately, that doesn't always work. However, EVERY time you buy something with your credits, your receipt will show you how many still remain. I think it is specific to the type of credit you just used, so if you use a snack credit to buy a pretzel, the receipt will show you how man snack credits are left. When you eat at a TS, you'll see your TS credits remaining.