Select the standard charge model if you want to charge the same price for each
unit consumed.Imagine that your API company charges $0.05 per API call (i.e. your billable
metric). By selecting the standard charge model, you will define a fixed unit
price. If a customer makes 1,000 API calls during the billing period, the total
invoice amount will be $0.05 x 1,000 API calls = $50.