A method and apparatus for saving, retrieving, and adjusting metering data uses information about the period between saves of the metering data to non-volatile memory and other information, for example, a number of recovery events experienced by the computer. The retrieved metering data may be adjusted according to the number of recovery events so that more frequent power interruptions cause metering data adjustments to favor a service provider. The time between data saves may be altered to increase the difficulty of timing attacks. Information about the time between saves, or the period of the save cycle, may also be stored with the metering data for use in the metering data restoration process.