I have a Web App that resides in example.com (non-WordPress, completely independent databases, etc) and I have a WordPress website, website.example.com and example.com/website.
Users will never log into WordPress, but they will access the WordPress website, then log into the Web App.
The Web App stores sessions and on the Web App pages I display this to show that the user is logged in:
echo “<a href='#' class='dropdown-toggle' data-toggle='dropdown'> Welcome, ".$_SESSION['full_name']." !</a>”;
How can I show this in WordPress if they change pages to the WordPress website?