This solution will NOT work with any website. You will have to use the author's login system. You will have major trouble trying to integrate this solution into your website. And the author will not help much.
All the AJAX files use a file called loader_ajax.php. There the author has included the following lines of code:
$_SESSION = array(
'username' => 'mike',
'user_id' => 1
$msg->logged_user_id = $_SESSION['user_id'];
So each time an AJAX call is made, this file fires up and CREATES NEW SESSION VARIABLES each time. These lines of code will overwrite the session variables that you have set with your own login system. In essence, there is no session data permanence. This is why this solution cannot be integrated into any website.
For example, my login system sets the session variable $_SESSION['user_id'] on successful login. This solution should have an easy way to reassign this session variable and pass the user_id to the various AJAX files using POST. That would make this solution worth purchasing.
I'm sure the author will take the time to respond to this critic. Maybe he should spend more time re-examining his code to make it easier to integrate with any website (as he claims it already does in the product description).