Any way to post an internal app that doesn't expire?

I'm a volunteer iOS programmer for a local church. I developed a giving kiosk app for them that works perfectly for their needs. I installed the app directly on their iPads from my laptop.

The problem is that it seems like the app "times out" and will refuse to launch. I'm not sure how often, after 6 months? 12 months? I bring in my laptop, reinstall the app and it's good for another 6-12 months.

Does it do that because the app is not published in the App Store? Is there any way to prohibit that behavior? Enrolling in the Enterprise Program is WAAAY overkill, since it's just a local church with a free non-profit developer account and it's just one app installed on 3 iPads.

I thought TestFlight might be a solution, but as I understand it, that would force me to publish an update every 3 months. That's even worse than the current situation.

Any suggestions?

Does it occur on all devices at the same time ? Or only when they upgraded to a new iOS version for instance ?

What is the exact message you get when app refuses to launch ?

This may be linked to your developer agreement validity (app must be re-signed, which is automatically done on the appstore), which lasts a maximum 1 year:

https://stackoverflow.com/questions/34435184/how-long-will-an-app-continue-to-run-on-my-ios-device-if-installed-via-xcode

In such a case, you should install as soon as you have renewed developer program to be OK for 1 full year.

Any way to post an internal app that doesn't expire?
 
 
Q