I don’t believe we enforce any rate limits on using your API key, so these will be limits enforced on the other end (Anthropic or OpenAI).
We have now enabled usage-based pricing for Pro users using premium models, which means if you exceed your 500 fast requests but don’t want to buy another 500, you can enable usage pricing.
For Claude 3.5 Sonnet, the cost is $0.04 per request ($20 / 500).