I think I wasn't clear enough that this is an annual subscription of significant cost ($300). With that in mind I would absolutely expect them to email in advance reminding me of the charge (other similar services do). I agree that for something that is monthly, I wouldn't expect an email every month.
Adding dates to the calendar and using giftcard/credit card are both good suggestions for the future.
Adding dates to the calendar and using giftcard/credit card are both good suggestions for the future.