I have a PPPoE connection and some clients. I dont know how to warn them to pay the money when the date comes and to program the system to cut their connection automatically when a certain date passes.
a) To cut off users, use centralized AAA and don’t just have accounts on the PPPoE server - or remember to go into the PPPoE server and disable the user account, and disconnect the client
b) http://wiki.mikrotik.com/wiki/Payment_Reminders: PPPoE payment reminders