MQTT Clients connect to a Server. When connecting to WebSphere MQ as the Server, there is a simple low cost (approximately $100) for that WMQ Server to be enabled to receive connections from MQTT clients - from any source. There is no limit to the number of clients that can be connected to a server under this license. There is a charge for each WMQ Server that is to have MQTT clients connected. But if any licenses of WMQ Advanced are purchased by a company, then that gives entitlement for all WMQ Servers to be enabled for MQTT connectivity without any additional charge.