What do AI credits cost, and how do I add more?

AI credits cost 25 cents each. To add more:

1. Go to Settings, then Billing.
2. Open the Usage tab.
3. Add funds, or turn on auto recharge. With auto recharge you can, for example, add $10 each time your balance falls below $10.

Your free and used credits show on the same Usage tab, in the AI assistant credits row.