You are allotted 250 miles per vehicle per month, with 125 miles per vehicle allowed for personal use. Days of vehicle drop off and pickup for rentals are not counted towards the monthly miles.
Off rental and personal mileage specifically extends to car maintenance, getting gas, drop-offs, pick-ups etc in-between turning on the app. You cannot use the Period X policies for personal trips. You should have personal auto coverage in place for personal use of the vehicle.