Effective Nov. 27, 2017, our pricing model has changed to benefit our API users, and we are no longer charge based on API utilization.
If you signed up before Nov. 27th, you received credits to allow you to test a proof of concept. We removed all credits and you were automatically enrolled in the Free Community Tier. The good news is the Community Tier is free forever and you don't have to worry about running out of credits!
All funds used to purchase additional credits and usage were applied to increased limits.