Based on your post and comments it appears he hasn’t paid you anything yet and you are several meetups in your first month. Did I understand you correctly? Also based on how you described his behavior I can confidently say you are being played. You’ll be lucky to receive anything. The pay at the end of the month “arrangement” is the oldest trick in the game for leaving you high and dry.

1. Get your compensation prior to intimacy. Always. Why? There is absolutely nothing you can do to make someone give it to you afterwards.
2. Stop giving out freebies and benefit of the doubt to people you don’t know. Trust is earned.
3. You should cut your losses with this guy. What little you may be able to get from him will be significantly lower than what you will have to give. He’s manipulating you with the promise of more. Words are cheap, and unfortunately for you, his actions are cheap too.