Hey Andrew,
You’ll need to delete this api key and create a new one as you’ve now exposed your key to the group in your email.
But to answer your question, you get an unlimited number of requests with a premium account, but not an unlimited amount of bandwidth, so the speed of your requests is indeed what is causing you to hit a rate limit. If you slow your script down a little bit, you should be good to go.
The sliding windows for the request rate limit are currently 20/second, 500/minute, or 5000/hour.
Just let us know if you have any other questions.
Cheers,
Garrison