What are cutoff days?

The "Cutoff days" feature, that can be found when creating a subscription rule, should allow your customers to not get billed twice in the set period of time. For an example: If you create a subscription that renews every month on the 15th and the customer purchases the subscription on the 13th, they should get billed again on the 15th. By setting the Cutoff days to 10 for an example, the subscription renewal should get skipped on the 15th, if the customer has purchased the subscription on the 13th.