Usage is free for all users, up to 100 queries per day.
Any usage beyond the free usage quota will fail if you are not signed up for billing. Once you have enabled billing, you will continue to receive 100 free queries per day. However, you will be billed for all additional requests at the rate of $5 per 1000 queries, for up to 10,000 queries per day. If you need additional quota, please request additional quota from the console.