If you've built an AI agent, the next question is simple: how do you charge for it?
Flat subscriptions don't fit AI workloads. Token costs vary by model, by direction (input vs output), and by how much each user actually consumes. One user might send 200 tokens a day. Another burns through 50,000. A flat fee either overcharges the light user or subsidizes the heavy one.
What you need is usage-based billing: each user pays for exactly what they use. In this tutorial, you'll build a sample AI agent and set up billing for it using FastAPI, OpenMeter, and Kong Metering & Billing (Cloud OpenMeter engine).
What is Usage-Based Billing?
Usage-based billing means charging customers based on actual consumption rather than a fixed amount. For AI agents, every API call has a measurable cost tied to token counts, and those costs vary by model. It's a natural fit.
