When you become a patron to a creator who is charging patrons "per post", you have the option of setting a monthly max to your pledge. This is so you are never charged more than you're comfortable with if the creator posts a ton of paid posts in a given month.
Here's how to set a monthly max:
From the Dropdown menu in the top right select . From there click "edit pledge" on the right hand side:
On the following page, select the checkbox next to "Optional: set a monthly max on your pledge". An option will appear asking you how many times per month you would like to contribute at max.
Don't forget to SAVE your changes by selecting update pledge on the right hand side!