If someone is onsite and gives consent, a reboot shouldn't cancel that consent. Often rebooting is needed to fix problems and clients cannot continually consent each time a machine is rebooted or network change is made. They especially can't do this if they are not there and give consent after hours!
Another alternative is when they click consent, have it default to 24 hours or something, with the option for the consenting user to change it to a different time limit if they prefer via a drop down box on the consent window. That way would work for everyone and still provide security in the instance a session was left open indefinitely.
Customer support service by UserEcho