If I don’t show up for a flight can I apply the value of the ticket in the future?

If by “don’t show up” you also mean don’t cancel, the answer is no. Most airlines today will allow a traveler to retain the value of an unused ticket (less an exchange fee, usually $200) toward the purchase of another ticket only if the traveler cancels the reservation prior to departure. Failure to cancel the reservation will forfeit the value of the ticket.