When to use usage based pricing

If your costs scale with usage then usage based pricing aligns your costs with your customers' spend. This prevents very large customers from being your worst customers, by generating lots of revenue, but costing you money because the account is gross-margin negative.

If you are pursuing a two step go-to-market strategy with which the first user has a low willingness to pay, but the ultimate buyer has a larger budget, consider usage pricing. This is a land-and-expand motion. 

If customers use the product intermittently and the value is intermittent, usage based pricing works well.