Hi Cjs --
In order for Go Button to run on iPhone and iPad, we are required to sell it through the App Store. And all App Store purchases are associated with the Apple ID that made the purchase. Unfortunately Apple does not provide a way to transfer a purchase to another Apple ID at this time.
As a reminder though, Go Button is free to download and use with one show. Your volunteers that do not have an unlocked copy of Go Button can still install the free version and have a fully functional app to use at least for one show at a time. And we support the free and unlocked versions just the same. Deleting a show from a device does not delete the audio files used by that show from the device, only the cue data. So you could AirDrop the audio files needed for all of your shows into Go Button on your volunteers' devices, then import each .gobutton show file you want to run as needed.
Copying shows between devices is explained in detail here in our documentation:
Brent