Your Mobile Apps do not expire.
What happens to a Mobile App if I delete a gallery?
Mobile Apps and galleries are actually completely different entities, so even if a gallery expires or is deleted, the Mobile App is unaffected. Regardless of the status of a gallery, the Mobile App will continue to work.
However, if you've linked a Mobile App to a gallery, that link would be broken if a viewer opened the App and clicked the "visit the gallery" link (since the gallery wouldn't exist or would be inactive).
What happens to a Mobile App if I delete it from my Studio Panel?
When you delete a Mobile App from your Studio Panel, the App will no longer work on devices where it has already been installed. If a client were to share the App via social media or by emailing the download link to someone else, the App will not be able to be installed.
ShootProof does reserve the right to remove Mobile Apps from your account if they have not been downloaded for more than a full year.