Expiring galleries make it easy for you to automatically revoke gallery access or free up server space at a time of your choosing. The built-in expiry tools are flexible and easy to set up. The idea is that you can "set it and forget it". If you agree to make images available for a client for a certain period of time, you can set up expiry and not need to keep track of it.
You can set up gallery expiry by navigating to the gallery in the My Images & Videos panel, then going to More / Gallery expiry. There are different kinds of behaviors you can set up for your gallery for different purposes.
Gallery never expires. This is the default setting for all galleries. No changes are made to the gallery, and it will remain available to your clients indefinitely.
Gallery expires, make gallery inaccessible at expiry. Once the chosen date of expiry is reached, the gallery will be made inaccessible to visitors. You can make it accessible again via the Authorizations panel of the gallery.
Gallery expires, delete gallery at expiry. The gallery is deleted, but all images are simply "unpublished" and kept on the server. Get easy access to your unpublished files by using the pre-existing Not Published smart collection, found at the bottom of the left-hand-side panel.
Gallery expires, delete gallery and its content at expiry.This setting permanently deletes the gallery AND the contained images. This cannot be undone! Use this setting to automatically free up space on your account when the images are no longer needed.