AI Agents Can't Use Subscriptions: The Case for Per-Call Settlement Rails

Traditional SaaS payment models—subscriptions, credit cards, and API keys—were designed for human users and don't serve autonomous AI agents that need real-time, transaction-based commerce. Agents require a fundamentally different infrastructure: per-call settlement with budget isolation and instant cost controls before tasks execute, not retrospective billing review. As AI agents become more autonomous, industry infrastructure must shift from pre-authorization to transaction-level settlement to enable safe, scalable deployment.