Beyond Subscriptions: Implementing Per-Request Payments with 402 Payment Required

Traditional API billing models built on API keys and monthly subscriptions fail to accommodate the bursty, task-driven usage patterns of autonomous agents. By leveraging 402 Payment Required, developers can move billing from a separate account layer into the HTTP transport itself, enabling request-level micropayments while keeping signing authority on the buyer's side. This architectural shift has major implications for how agent-driven APIs are monetized and consumed.