The free Linux plan on CircleCI has 1,500 minutes of build time available per month: https://circleci.com/pricing
We have recently started enforcing the limit. This is the reason you may see:
Your build was not run - reason code (:org-over-credit-limit)
All customers who are affected by this should have received an email in preparation for the change.
Your monthly cycle is based on the date your org was created on CircleCI (not necessarily 1st of the month).
You can upgrade to a paid plan to remove the build minutes limitation.
If you’re building an Open Source project you can request your project be covered by our Open Source plan which will remove the minutes limitation.
The limit is to prevent abuse of the platform so we can provide the best service for everyone.