Cookies expire time frame

i thought I posted this before but Id like to know if the cookies expire after a given time and if not, can I make them expire?

function wpfp_set_cookie($post_id, $str) {
    $expire = time()+60*60*24*30;
    return setcookie("wp-favorite-posts[$post_id]", $str, $expire, "/");

this part of the code makes me think that it will expire or I should be able to tell the system when the cookies should expire.

https://www.ads-software.com/extend/plugins/wp-favorite-posts/