Apphi gives each account 10 free autoposts per month. But the refill of the free autopost does not necessarily happen on the first day of each month. It is instead calculated based on your registration date.
For example, you registered on May 5th, you will see your free autopost refill on June 5th, July 5th, etc. If you then subscribe to a monthly/yearly plan on August 10th, your free autoposts will still refill on the 5th of each month.