Node app member access

I have node.js applications running on my subdomain. I want only to allow members to access. I currently have a Wordpress site that uses simple membership that I just added. The node.js app is accessed once a member logs in. Iframe is used to open the app in my Wordpress site. Unfortunately this is not secure as the url is visible. Is it possible to have the node apps check that a valid user is logged in? I also want to add two factor authentication to some apps. I want full documentation so I can add other node apps later. I cannot give you access to site so I will make the modification. Some may only use the primary member login and other may use the two factor.