Grok’s paid plans start at $20/month and include up to 10 prompts every 2...

https://johnathankvdj950.wpsuo.com/how-does-grok-api-storage-billing-work-per-gib-per-day

Grok’s paid plans start at $20/month and include up to 10 prompts every 2 hours, suitable for steady users. There’s no free trial, so you pay from day one