Laravel: comprobación de solo una sesión

// users alter table
Schema::table('users', function(Blueprint $table){
    $table->string('session_id')->nullable();
}


// on Auth/LoginController.php
// add this function
public function authenticated(Request $request,User $user){
    $previous_session = $user->session_id;

    if ($previous_session) {
        \Session::getHandler()->destroy($previous_session);
    }

    Auth::user()->session_id = \Session::getId();
    Auth::user()->save();

    return redirect()->intended($this->redirectPath());
}