独特的会话WordPress

I want to allow only one session at the time across browsers and PCs. I want to "disconect" or log out to the old session if a new session starts in Wordpress.

Seems you would hook into the account sharing function and expire the session from there. I think there will still be some limited access, the expired user may still have while their cookies remain on their system. This functionality does not exist. You would need to develop a plugin.

You can start from here: http://www.frank-verhoeven.com/using-session-in-wordpress/

Note: Maybe you get better answers from here

Include the following code at function.php

function kana_init_session()
{
  session_start();
}

add_action('init', 'kana_init_session', 1);

It works for me & believe it works for you too. I learn the trick from HERE.