Users should be charged $10 whenever they make a sale, provided that is the first sale of a given month.
For example:
The user makes a sale on June 3rd, 4th, and 5th. They will be charged $10 for the sale on the 3rd.
The user does not make any sales during July. They will not be charged $10 for July.
The user receives a donation for a free addon during August. They will not be charged $10.
Users should be charged $10 whenever they make a sale, provided that is the first sale of a given month.
For example: The user makes a sale on June 3rd, 4th, and 5th. They will be charged $10 for the sale on the 3rd. The user does not make any sales during July. They will not be charged $10 for July. The user receives a donation for a free addon during August. They will not be charged $10.