Best solution is of course to switch to B4XPages.
The starter service will never be killed, as long as the process running.
It isn't possible to make other services behave the same, unless you prevent them from being killed by making them foreground services.
With or without B4XPages, if you want your app to run in the background, you need a foreground service.
Note that the starter service shouldn't be set as a foreground service.