If you are interesting is creating an App for your WishList Member site, there are a number of options available to look into.
The BuddyBoss App allows you to create mobile apps for your course or community. This allows for the creation of your own membership App and they have made BuddyBoss App integrate with WishList Member.
The team at BuddyBoss are able to provide more specifics on that option.
Another option for developing an app is AppMySite. It include a free trial and can be used to create an app for your membership site/community.
That all being said, we recommend checking out this article with more options (and examples) when it comes to converting a WordPress site into an App.