What does ionic push service provide?

My friend who do native android said push notification is tedious and he said have to check if the token expired, and have to save the latest generated token to the db.

So what does ionic push service provide? as I know every time I do this

 push.register(function(token) {
      console.log("Device token:",token.token);
      push.saveToken(token);  // persist the token in the Ionic Platform

I’m seeing the same token every time I open my app, unlike what he said I will get a whole new token. And how do I clean up my token in db? like I have 100,000 app download and have 100,000 token saved in the db, but over time there might be only 20,000 active user, it’s a waste to send 100,000 token again right? how to handle that case?

hi, i currentely have push sort of working for me. I have receive push and see the push msg after i reinstall the app from CLI. But looks like, after some times, i have sens my push, but i cant receive on my device.

is it has any expiry time on each device token? or because i use the dev push true mode, this coz the not receiving push issue?

any idea? thanks.