Andy is correct. As long as you include session_start(); on a subsequent page, you can access your session variables until the browser (all windows) are closed or the session times out (generally about 20 minutes...check your php settings to be sure).

I believe that you are also correct about session_register. That was copied from some code that's at least 7 years old, so some things have changed a bit. For example, it also assumes that register_globals is on, which is clearly a no-no these days.