How to enable HTTP connection keep-alive or persistent (some call it http reuse)?

Hello, I am wondering the same thing. I want to automate a login. On the website a key is in the main page and just for a POST request after you submit the login. My quess is that after my first GET action to retrieve the key the "login page" closes and on the backend the key is not valid anymore so the POST uses an old key. Could this be happening?

Did you solve it or can you suggest me some tools to look what is happening?

actually, I just opened a post regarding my case with more info. If needed it is here