stay authenticated php youtube application Youtube API - php

Question

I'm building an php application which receives videoID's from youtube.
but if i authenticate the application with the youtube account it displays the upload videos correctly. If i remove the session or try an other browser it is required to authenticate the application again.
here is my source:
http://pastebin.com/7GezyHZs
my client_secrets.son looks like:
{
"web": {
"client_id": "clientID.apps.googleusercontent.com",
"client_secret": "CLientsecret",
"redirect_uris": ["https://localhost/oauth2callback.php"],
"auth_uri": "https://accounts.google.com/o/oauth2/auth",
"token_uri": "https://accounts.google.com/o/oauth2/token"
}
}
(credentials removed)
my oauth2callback.php looks like:
<?php
require_once 'google-api-php-client/autoload.php';
session_start();
$client = new Google_Client();
$client->setAuthConfigFile('client_secrets.json');
$client->setRedirectUri('http://' . $_SERVER['HTTP_HOST'] . '/oauth2callback.php');
$client->addScope(Google_Service_Drive::DRIVE_METADATA_READONLY);
if (! isset($_GET['code'])) {
$auth_url = $client->createAuthUrl();
header('Location: ' . filter_var($auth_url, FILTER_SANITIZE_URL));
} else {
$client->authenticate($_GET['code']);
$_SESSION['access_token'] = $client->getAccessToken();
$redirect_uri = 'http://' . $_SERVER['HTTP_HOST'] . '/';
header('Location: ' . filter_var($redirect_uri, FILTER_SANITIZE_URL));
}
is it possible to authenticate with google for ever?
Thank you in advance.