Charles Schwab's API team enforces a 7 day reconnect rule. This means that if you don't reconnect your account every 7 days then they will break the connection.
This is the most secure way to handle broker connections, but it is tedious and annoying. This is a small cost to using Charles Schwab that you need to be aware of.
Our system will send you an email a day or two before you need to reconnect as a reminder. Once you broker disconnects, you will receive an email as well.