function be_set_cookie() {
if( empty( $_GET['partner_id'] ) )
return;
setcookie( 'billericksonPartnerId', intval( $_GET['partner_id'] ), time() + 3600 * 24 * 45, COOKIEPATH, '.' . str_replace( [ 'http://', 'https://', 'www.', 'www' ], '', home_url() ), false );
}
add_action( 'init', 'be_set_cookie' );
// To access cookie:
// $_COOKIE['billericksonPartnerId'];