If it is a server (web) app, you are in control ! (updated your B4J server app whenever you want).
If it is a device app (Android or iOS), you can post them on GooglePlay or iStore, or you can host them yourself on your website - for users to update.
I have a private server at a remote location which checks if a newer app is available to download - for an ANDROID device (checks current version number with server version number). If version on server is a higher number, it downloads it - and asks the user to install it (Android permission restriction). Works well.
IF this is a program that runs on a clients machine (old way of doing things these days - everything is web / server based) - well then I don't know...
Thanks