This topic covers the emerging set of pay‑per‑use and account‑free API patterns that enable autonomous AI agents to transact, purchase services, and settle micro‑payments without requiring persistent end‑user accounts. Driven by agent marketplaces, automation platforms, and new payments primitives, these capabilities include metered billing endpoints (Pay.sh–style pay‑per‑call APIs), blockchain‑enabled account abstraction (examples of Google Cloud integrations with Solana), and conventional/crypto rails for fiat on‑ramp and payouts (Stripe and Coinbase agent payment flows). Relevance and timing: by 2026 many teams are moving from prototype agents to production deployments that must handle small, high‑frequency transactions, privacy‑preserving credentialing, and regulatory compliance. Marketplaces and toolchains need predictable, low‑latency billing and flexible settlement options to support microtransactions and third‑party service purchases. Visa Intelligent Commerce, for example, signals mainstream payments incumbents building primitives that let agents discover and buy goods securely. Key tools and roles: Vertex AI and similar cloud ML platforms provide model hosting, orchestration and observability for agents; Replit and agent IDEs accelerate building and deploying agent-driven services; Qodo (formerly Codium) focuses on quality‑first development, code review and SDLC governance for complex agent codebases; payment primitives (Pay.sh‑style APIs, Stripe/Coinbase rails, and blockchain integrations) handle metered charging, conversion, and settlement. Practical considerations include fraud and risk controls, latency and cost tradeoffs for on‑chain vs off‑chain settlement, user consent and privacy for account‑free flows, and developer tooling for instrumentation and reconciliation. Together these pieces define a practical stack for commercializing autonomous agents across marketplaces and automation platforms.