To explore and experiment with the API, all new users get free $5 worth of free tokens. These tokens expire after 3 months.
After your trial period has passed, you can choose to enter billing information to upgrade to a paid plan and continue your use of the API on pay-as-you-go basis. If no billing information is entered you will still have login access, but will be unable to make any further API requests.
Please see the pricing page for the latest information on pay-as-you-go pricing.