Remove the register link from wp-login.php. On a membership site you may not wish members to self register.

/*------------------------------------------------------------*/
// Remove the register link from the wp-login.php script
/*------------------------------------------------------------*/
add_filter('option_users_can_register', function($value) {
    $script = basename(parse_url($_SERVER['SCRIPT_NAME'], PHP_URL_PATH));
    if ($script == 'wp-login.php') {
        $value = false;
    }
    return $value;
});

Code language: PHP (php)