User Registration to Subscription (wpmu)

code.php

<?php
/*
Plugin Name: User Registration to Subscription (wpmu)
Plugin URI: http://bappi-d-great.com
Description: This plugin allows your users to auto subscribe when registered
Author: WPMU DEV
Version: 1.0.1
Author URI: http://bappi-d-great.com
*/

if( class_exists( 'Incsub_Subscribe_By_Email' ) ){
	add_action( 'user_register', 'user_register_cb', 10, 1 );
	function user_register_cb( $user_id ) {
		$user_info = get_userdata( $user_id );
		Incsub_Subscribe_By_Email::subscribe_user( $user_info->user_email, 'Manual Subscription', 'User Registration', false, array() );
	}
}