"Usage fees" refers to charges or payments that are required when you use or access certain services, facilities, or resources. It is a fee that must be paid based on how much the service or resource is utilized or used. Full definition
Student accounts often have few, if any, maintenance and debit card usage fees. (sapling.com)
Then customers pay usage fees, based on how long they ride. (inc.com)
For a set - up fee of $ 25 and a $ 25 monthly usage fee, subscribers can use the service to compose and transmit up to 2,500 e-mail messages each month. (realtormag.realtor.org)