Create an email to the host , advising that he may need to reach out with his guest via the app messaging and have an agreement that he will pay for the gas invoice and stating the amount.

Subject: Coordination Regarding Gas Invoice Dear [Host's Name], I hope this message finds you well. I wanted to advise you that it may be beneficial to reach out to your guest via the app messaging feature for any further coordination regarding their stay. Additionally, please note that we have agreed that you will be responsible for covering the gas invoice, which amounts to [insert amount]. If you have any questions or need further assistance, feel free to reach out. Best regards, [Your Name] [Your Contact Information] [Your Position/Role, if applicable]