By checking the “Countdown” box you can activate this option in your plan settings. Countdown plans are used when you only want to offer a plan for a limited period of time – after that they will be automatically hidden. You can use them for special promotions, like offering a very cheap plan for two days only, for example.
After the expiration date, members will no longer be able to purchase this plan. However, everyone who booked it before the expiration date will remain a member of this plan.