I am currently using Zapier’s free plan (yay!) and recently got this email:

Just a heads up: You're now over 80% of your Zapier task limit for this billing period. When you reach 100% of your task limit, we’ll start holding your tasks. Held tasks will be stored in your Task History, but won’t be completed until you upgrade your account.

To make sure your Zaps continue working for you, we recommend you upgrade your plan.

So I need to know--when does each “billing period” end (and the next one start) and this task limit counter reset? Every 1st of the month? 7th? 15th? Please let me know.