By default, Ongoing will charge them immediately (within 24 hours) if their next billing date was in the past

If the original next billing date is after the unpause date: This means that if the subscription was set to be billed at a future date that is later than the date you plan to resume (unpause) the subscription, the billing will adhere to the original schedule. In other words, the customer won't be charged until the original next billing date arrives, even if the subscription is resumed earlier.

If the original next billing date is before or on the unpause date: In this scenario, where the billing date has already passed or coincides with the date the subscription is resumed, the customer will be charged immediately upon unpausing.

This rule ensures that billing is managed fairly in relation to the pause and resume actions on a subscription, preventing customers from being charged while their subscription is paused and defining clear guidelines for when billing will resume.