How to log in to third party websites?

Well, to be very clear, I made a login screen that sends a “POST” method to a third party login site, it works fine, everything returns normal.

The problem that occurs is when I want to go ahead, open a new screen that will still be logged in, but how can I do that, if I can’t get the session I started with a “Web” component and insert it into “Web Viewer”, I don’t think it’s possible.

(NOTE: I do not have access to a database, I only use the “POST” of the Web Component)