Single Authentication for multiple laravel Application

I have 3 laravel Applications with 3 databases. Application 1 is the Login for authentication (Registrations and Login) and is only connected to the users Database .

Application 2 allows user to perform some basic operations and is connected both to user and App2 Databases

Application 3 allows users to perform some other operations different from application 2 and is connected to users and App3 Databases

Now my problem is to allow a user looggin once through Any of the applications and is automatically logged in to other application

More like having a single google account that works in all apps.

Application 1 will be access through the main URL

  www.kokoka.com

while others will be access through

  health.kokoka.com
  school.kokoka.com

I have tried http://ift.tt/2pLjwXc

I have also changed the Domain in session.php

  'domain'=>'.domain.dev'

all to no avail

via Chebli Mohamed