google plus login api cookie - google-app-engine

Question

I am using google app engine python. I followed the example code to let user login. After this step am I supposed to create my own cookie or session to remember the user? Because when i refresh the page, the login button appears again.
This is the javascript.
<script src="https://apis.google.com/js/plusone.js" type="text/javascript"></script>
<script type="text/javascript">
/*
* Triggered when the accepts the the sign in, cancels, or closes the
* authorization dialog.
*/
function loginFinishedCallback(authResult) {
if (authResult) {
if (authResult['error'] == undefined){
gapi.auth.setToken(authResult); // Store the returned token.
toggleElement('signin-button'); // Hide the sign in upon successful sign in.
getEmail(); // Trigger request to get the email address.
} else {
console.log('An error occurred');
}
} else {
console.log('Empty authResult'); // Something went wrong
}
}
/*
* Initiates the request to the userinfo endpoint to get the user's email
* address. This function relies on the gapi.auth.setToken containing a valid
* OAuth access token.
*
* When the request completes, the getEmailCallback is triggered and passed
* the result of the request.
*/
function getEmail(){
// Load the oauth2 libraries to enable the userinfo methods.
gapi.client.load('oauth2', 'v2', function() {
var request = gapi.client.oauth2.userinfo.get();
request.execute(getEmailCallback);
});
}
function getEmailCallback(obj){
var el = document.getElementById('email');
var email = '';
if (obj['email']) {
email = 'Email: ' + obj['email'];
}
//console.log(obj); // Uncomment to inspect the full object.
el.innerHTML = email;
toggleElement('email');
}
function toggleElement(id) {
var el = document.getElementById(id);
if (el.getAttribute('class') == 'hide') {
el.setAttribute('class', 'show');
} else {
el.setAttribute('class', 'hide');
}
}
</script>
This is the login button.
<span id="signin-button" class="show">
<div class="g-signin" data-callback="loginFinishedCallback"
data-approvalprompt="force"
data-clientid="279937419542.apps.googleusercontent.com"
data-scope="https://www.googleapis.com/auth/plus.login
https://www.googleapis.com/auth/userinfo.email https://www.googleapis.com/auth/plus.me https://www.googleapis.com/auth/userinfo.profile"
data-height="short"
data-cookiepolicy="single_host_origin"
>
</div>
</span>