Membership 2 : Its a custom add-on to limit the number of blog a member can create within a membersihp. Dependent on membership attributes add-on.

gistfile1.txt

<?php 
/**
 * Plugin Name: Membership 2 Site Limitation
 * Version:     1.0
 * Description: Limit number of blogs a member can create on multisite.
 * Author: Sajid Javed From Incsub
 * Author URI:  http://premium.wpmudev.org/
 */
 
 class MS_Custom_Addon_Sitelimit {
	/**
	 * A unique Add-on ID, prefix with "custom_" to avoid collissions
	 */
	const ID = 'custom_addon_sitelimit';
	
	/**
	 * This is the slug of the custom attribtue which defines the site-limit.
	 */
	const ATTR_SLUG = 'max-sites';
	
	/**
	 * This is the slug of the custom attribtue message to display when member reached the limit
	 */
	const MAX_LIMIT_REACH_MESSAGE = 'max-limit-message';
	
	static public function init() {
		// Those actions are only called by the M2 plugin, so we do not check
		// if M2 is active or not:
		// If M2 is not active, then those actions are never triggered.
		//add_action( 'ms_model_addon_initialize', array( __CLASS__, 'sl_init' ) );
		if( class_exists( 'MS_Plugin' ) )
			add_action( 'init', array( __CLASS__, 'sl_init' ) );
			
		add_filter( 'ms_model_addon_register', array( __CLASS__, 'register' ) );
	}
	/**
	 * Checks if the current Add-on is enabled
	 *
	 * @return bool
	 */
	static public function is_active() {
		return MS_Model_Addon::is_enabled( self::ID );
	}
	/**
	 * Initializes the Add-on. ALWAYS EXECUTED, EVEN WHEN DISABLED.
	 */
	public function sl_init() {
		if ( self::is_active() ) {
			if ( ! MS_Model_Addon::is_enabled( MS_Addon_Attributes::ID ) ) {
				echo 'This Add-on requires the Membership Attributes Add-on';
				return;
			}
			global $pagenow;
			
			if($pagenow != 'wp-signup.php' and !isset($_GET['action']) and $_GET['action'] != 'new_blog'){
				return;
			}
			
			$api = ms_api();
			$real_limit = 0;
			
			// Find the max limit for current user.
			$member = $api->get_current_member();
			$user_id = $member->id;
				 
			if($member->subscriptions){	
				foreach ( $member->subscriptions as $subscription ) {
					// Read the attribute value from a membership.
					$cur_limit = ms_membership_attr( self::ATTR_SLUG, $subscription->membership_id );
					$max_limit_message = ms_membership_attr( self::MAX_LIMIT_REACH_MESSAGE, $subscription->membership_id );
					
					// Use the highest limit that the user has access to.
					$cur_limit = intval( $cur_limit );
					if ( $cur_limit > $real_limit ) {
						$real_limit = $cur_limit;
					}
				}
			}
			
			$user_blogs = get_blogs_of_user( $user_id );
			
			$blog_count = 0;
			
			if($user_blogs){
				foreach ($user_blogs as $blog){
					$blog_admins = self::site_admins($blog->userblog_id);
					
					if( in_array($user_id, $blog_admins ) )
						$blog_count++;	
					
				}
			}
 			
			if( $blog_count >= $real_limit and ( !empty($real_limit) || $real_limit != 0) ){
				if(empty($max_limit_message))
					$max_limit_message = 'You reached the maximum blog limit. Please upgrade to create more.';
				wp_die( $max_limit_message );
			}
			
			// Now you have the $real_limit, rest is up to you ;)
			// Add your custom hooks and add-on logic here.
		}
	}
	
	/**
	 * Get blog admins
	 * param: $blog_id
	 * return: array of admin ids
	 */
	static public function site_admins($blog_id)	{   
		$site_admins = '';
		switch_to_blog( $blog_id );
		$users_query = new WP_User_Query( array( 
					'role' => 'administrator', 
					'orderby' => 'display_name'
					) );
		$results = $users_query->get_results();
		foreach($results as $user)
		{
			$site_admins[] = $user->ID ;
 		}
		restore_current_blog();
		return $site_admins;
	}
	/**
	 * Make the Add-On appear in the Add-on list.
	 *
	 * @param  array $list The Add-Ons list.
	 * @return array The updated Add-Ons list.
	 */
	public function register( $list ) {
		$list[ self::ID ] = (object) array(
			'name' => __( 'Site Limitation', 'text-domain' ),
			'description' => __( 'Custom Addon description. Required Membership Attributes', 'text-domain' ),
			 
		);
		 
		
		return $list;
	}
	
}; // End of the custom Add-on class.
add_action( 'plugins_loaded', array( 'MS_Custom_Addon_Sitelimit', 'init' ) );