The "$10.00 per month + taxes" prepaid plan, does it expire monthly or every 30 days? If it's every 30 days, then why does it say "monthly?" (The reason why this is a relevant question is that you can set up a bank account to direct a payment on the same day of each month, but it does not allow a payment every 30 days... and I don't want surrender my bank account or my credit card to anyone)