You can use any existing user management. Either your userids (integer) or any string key (email, username, IP-Address) can be used to identify your users. You should also tell the class if your user is authenticated or not. On this demo page I set the auth-value automatically to true and used your IP addresses as key to identify you. Just include SBM script on every page where you like to offer bookmark function, initialize class and show form or bookmarks.