How can I limit submissions to 1 per IP address for the month?

 Also, is there a way to reset it so someone may submit again the next month?

I think you can take a look at this guide

https://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form

Strict Check will control the IP address. However, if IP does not change in a month (some ISP will do it) , then the user will not be able to submit a new one next month.

You might probably set an expiration date and/or a number of submissions limit the form can receive.

Be aware that if you put 1 at the Submission Limit option, that doesn't mean it's one per user, it means the form will get only one submission as a whole total.