Anysphere, the company behind Cursor, switched the Pro plan from a flat request count to usage-based billing in June 2025, causing monthly costs to swing significantly. A normal week of Agent-mode refactoring can push a $20 Pro subscription past its included credit. One fix is bringing your own API key (BYOK), which involves connecting your own OpenAI, Anthropic, Google, Azure, or AWS Bedrock account and paying each provider directly at its published rate instead of using Cursor’s shared credit pool. The tutorial covers a 13-step setup, including generating and locking down keys, wiring them into Cursor, building a break-even calculator, and writing two Python scripts to monitor spend and send Slack alerts. Budget about 65 minutes if you already have accounts with at least two of the providers involved. Before June 16, 2025, Cursor Pro subscribers got 500 “fast” premium requests a month. After that date, Pro switched to roughly $20 of usage priced close to each model’s own API rate, plus unlimited access through Cursor’s Auto mode.