Rendering credits are reset on the 1st of every month, regardless of your billing date. This policy is more generous to users because it allows them to write off both the maximum usage of the month when the subscription starts and the maximum usage of the month when it ends.
We also run this monthly policy for a consistent user experience. For example, if you have unused credits last month, they are all written off first and then topped up with new credits this month. The month is based only on the unused portion of the previous month, and there is no order to exceed the current plan’s maximum credits. (If you downgrade the plan after the month has passed, the credits that exceed the maximum for that plan are not carried over.)