Am I required to pay the toll for each day my vehicle stays within the Congestion Relief Zone? 

No. You are not required to pay the toll for each day your vehicle remains within the Congestion Relief Zone. The toll is only charged when your vehicle enters the Congestion Relief Zone. If your vehicle stays parked within the zone or if all trips made on a particular day are entirely within the zone, you will not be charged for that day. This means that as long as your vehicle does not cross into the zone from outside, no toll will be applied for that day.