You two are faggin up the thread with BS.
You could try playing with session_set_cookie_params which ive had no luck with, or you can construct your own cookie like (after session_start): setcookie(session_name(), session_id(), time() +31536000, "/");
The expiry time on the cookie is a year, BUT the sessions will not last that long.
Because of the Garbage Collection, the sessions will be removed long before the cookie expires. If you have access to the PHP.ini you can change the GC lifetime and probability, if you dont have access then... you are fucked i guess.