How does the interface count work?
Each data stream, inbound or outbound, requires one ConnectIT 365 interface definition. So, if your sales order exchange with a customer consists of one data stream that is requesting new orders, and one which is sending an acknowledgement back to that source system. That integration is made up out of 2 interfaces in total.
The total count of all active definitions, minus one, is what is used to validate your license. Why minus one? That is because every customer gets one interface definition for free.