Hi, my use case is:
1. Customer purchases a subscription (all easy with Squarespace, or sentrylogin etc)
2. They get an account, with profile and password reset etc (all easy with Squarespace, or sentrylogin etc)
3. They have secure access to a page of user settings for an external app (ie a page that allows them to update fields in a database) based on username (and the fact they have authenticated with their Squarespace or sentrylogin customer account).
The page of settings I can do, if I had access to an authenticated user ID but Squarespace and sentrylogin do not provide access to this info. I don't want to build my own commerce site and user management system of course but have had no luck finding a solution I can buy?