Methods, systems and computer program products for tracking a client's usage of one or more services provided by one or more servers. A client generates and sends one or more metering packets to a census service. Each metering packet includes a time element indicating the client's usage of the one or more services. The time element may include a charged time portion and a free time portion. An authentication element may be included with each metering packet so that the census service can determine whether or not a given metering packet is genuine. A login service communicates to the client whether or not usage should be tracked and indicates a time interval to expire between subsequent metering packets. A session identifier in each metering packet allows multiple sessions to be tracked simultaneously. Upon receiving metering packets, the census service discards redundant metering packets and updates a usage database accordingly.