Background service running indefinitely

I have an application that I want to receive at any moment a push notification, but the problem is that the user can close the app, probe the Background Mode “” but it only works while the app is open or in the background and was not deleted after this does not work, what I look for is similar to what does whatsapp do to receive a message despite the fact that the app is closed

Using push notifications doesn’t require your app to be open in the background.

I have the problem that a that executo closes the connection and also the notifications do not arrive until unlock the phone and launch the application of background