Often it’s to give the airport owner/operator a way to further monetize “underutilized” land-side space by leasing it to an airline/lounge operator; and the lease-paying lounge operator makes use of the space as part of a business to provide a way for arriving passengers to shower up, grab some food and beverages, and do some work/tasks before heading out of the airport and into the city of arrival. Pay-per-use means the lounge operator levies a charge per user of the lounge; and the payer could be an airline, a lounge membership program, and/or those individuals who show up at the lounge check-in desk and are willing to whip out some money for one-time lounge use.