how can i get ionic app keep connected(authentification) even i closed it
Hi @Ines89 
You can store the token or auth credentials in the devices storage and read it from there, so it works after restarts.
I recommend you to check out Ionic Storage for this, as it automatically selects the place place to store your data (SQLite, IndexedDB, LocalStorage), it works in the browser and it’s really easy to use: https://ionicframework.com/docs/native/native-storage
Best,
Rodrigo