This is a question from August 2013. I have the same issue. Has this been implemented yet?
“How do I setup my account to limit the allowable maximum number of API calls per day/week/month?
I was not able to find it under the MyAccount or Billing tabs.”
2013 Answer:
“We do no impose or place limits on the number of requests you can make per day. It is the responsibility of your application to control the request rate if you want to have your own restrictions. However, we are investigating the possibility of implementing server-enforced usage limits for the next version of FlightXML.”