"Pinning" a ticket just means that you'll always be in possession of the ticket. It pins it to the Agent so replies, follow-ups aren't returned to the queue where it can be handed to a different Agent. However, it still follows the same behaviors as non-pinned tickets. So it's not a like a follow-up flag in email that may require follow up or anything. For that, you'd in the ticket then schedule a follow-up for it.