Your payment history is available at https://app.getpostman.com/pay/history. If you notice multiple charges to your card on the same day, it's probably our system retrying older payments that failed.
If your team is on Postman Pro, requests made over your Monitoring limit will be charged at $0.75/1000 requests. These charges will not necessarily be made at the same time as your Pro renewal charges. More info on this can be found here
No invoice item will be charged to your card more than once.