Can I turn off the Agent while it's not being used?

ANSWER  Yes.

The Agent is not required to be online until it is required to perform an assessment. During this time, however, you may receive a notification that the Agent is offline. If the Agent is found to be offline during the time that the assessment is scheduled to run, the assessment will be rescheduled to the next allowed scanning day/time.

IMPORTANT  In order to allow the Agent to update itself and prepare the necessary files used for the penetration test, it is recommended to turn the Agent on at least one to two hours prior to the assessment kicking off.