# Models and keys

> Which model an Agent host agent uses: your own key on Pro, the built-in AI on Premium and Max, and model tiers haiku, sonnet and opus.

Source: https://agenthost.geenius.io/docs/models-and-keys/

**Pro.** Add your own model key. It is sealed and never shown again. Only your provider's model is called with it, and the deployment's keys are never used for a Pro workspace.

**Premium and Max.** The built-in AI answers, and the deployment's keys are used. A model step costs credits by tier.

You choose the tier in the agent's setup: haiku, sonnet or opus.