Overview

This system enables selling WordPress plugins with license validation and automatic updates. Built on FluentCart Pro’s licensing module, it provides a complete solution for plugin distribution and license management.

Architecture

The system uses a two-plugin architecture:

Two Plugins Required

License Workflow

POST https://your-site.com/wp-json/fluent-cart/v1/license/activate
Body: {
  "license_key": "YOUR_LICENSE_KEY",
  "site_url": "https://customer-site.com"
}

Critical Implementation Details

// CORRECT:
$site = LicenseSite::firstOrCreate(['site_url' => $site_url]);
$site = LicenseSite::where('site_url', $site_url)->first();

// WRONG (will cause SQL error):
$site = LicenseSite::firstOrCreate(['url' => $site_url]);

// Accept inactive licenses (unused)
if ($license->status === 'inactive') {
    $license->activate(); // Changes status to 'active'
}

// Only reject suspended or expired licenses
if ($license->status === 'suspended') {
    return new WP_Error('suspended_license', 'License is suspended');
}

# Create temp folder
New-Item -ItemType Directory -Path "temp-flat" -Force

# Copy ONLY essential files (NO releases folder!)
Copy-Item "your-plugin.php" "temp-flat\"
Copy-Item "VERSION" "temp-flat\"
Copy-Item "CHANGELOG.md" "temp-flat\"

# Compress contents (use \* wildcard for flat structure)
Compress-Archive -Path "temp-flat\*" `
    -DestinationPath "your-plugin-v1.0.X.zip" -Force

# Clean up
Remove-Item "temp-flat" -Recurse -Force

Server Plugin Implementation

REST API Endpoints

License Activation Handler

function handle_license_activate($request) {
    $license_key = $request->get_param('license_key');
    $site_url = $request->get_param('site_url');
    
    // Find license
    $license = License::where('license_key', $license_key)->first();
    
    if (!$license) {
        return new WP_Error('invalid_license', 'Invalid license key');
    }
    
    // Validate
    if ($license->isExpired()) {
        return new WP_Error('expired_license', 'License has expired');
    }
    
    if ($license->status === 'suspended') {
        return new WP_Error('suspended_license', 'License is suspended');
    }
    
    // Check activation limit
    $current_activations = LicenseActivation::where('license_id', $license->id)
        ->where('status', 'active')
        ->count();
    
    if ($license->limit > 0 && $current_activations >= $license->limit) {
        return new WP_Error('activation_limit_reached', 
            'Activation limit reached');
    }
    
    // Create site (CRITICAL: use 'site_url' not 'url')
    $site = LicenseSite::firstOrCreate(['site_url' => $site_url]);
    
    // Create activation
    LicenseActivation::create([
        'site_id' => $site->id,
        'license_id' => $license->id,
        'status' => 'active'
    ]);
    
    // Activate license on first use
    if ($license->status === 'inactive') {
        $license->activate();
    }
    
    return rest_ensure_response([
        'success' => true,
        'message' => 'License activated successfully',
        'data' => [
            'license_key' => $license_key,
            'status' => 'active',
            'activation_count' => $current_activations + 1,
            'activation_limit' => $license->limit
        ]
    ]);
}

Client Plugin Implementation

License Activation (Admin Interface)

function handle_license_activation() {
    $license_key = sanitize_text_field($_POST['license_key']);
    $site_url = home_url();
    
    $response = wp_remote_post(
        'https://your-site.com/wp-json/fluent-cart/v1/license/activate',
        array(
            'body' => json_encode(array(
                'license_key' => $license_key,
                'site_url' => $site_url
            )),
            'headers' => array('Content-Type' => 'application/json')
        )
    );
    
    $body = json_decode(wp_remote_retrieve_body($response), true);
    
    if ($body['success']) {
        update_option('your_plugin_license_key', $license_key);
        update_option('your_plugin_license_status', 'active');
        update_option('your_plugin_license_data', $body['data']);
    }
}

Daily License Check (Cron)

function daily_license_check() {
    $license_key = get_option('your_plugin_license_key');
    
    $response = wp_remote_post(
        'https://your-site.com/wp-json/fluent-cart/v1/license/check',
        array(
            'body' => json_encode(array(
                'license_key' => $license_key,
                'site_url' => home_url()
            )),
            'headers' => array('Content-Type' => 'application/json')
        )
    );
    
    $body = json_decode(wp_remote_retrieve_body($response), true);
    
    update_option('your_plugin_license_status', $body['data']['status']);
    update_option('your_plugin_license_last_check', time());
}

// Register cron event
add_action('your_plugin_daily_license_check', 'daily_license_check');

Update Check (WordPress Hook)

function check_for_updates($transient) {
    if (empty($transient->checked)) {
        return $transient;
    }
    
    $license_key = get_option('your_plugin_license_key');
    $plugin_data = get_plugin_data(__FILE__);
    
    $response = wp_remote_post(
        'https://your-site.com/wp-json/fluentcart/v1/plugin-update-check',
        array(
            'body' => json_encode(array(
                'plugin_slug' => 'your-plugin',
                'current_version' => $plugin_data['Version'],
                'license_key' => $license_key,
                'domain' => home_url()
            )),
            'headers' => array('Content-Type' => 'application/json')
        )
    );
    
    $update_data = json_decode(wp_remote_retrieve_body($response), true);
    
    if (version_compare($plugin_data['Version'], $update_data['version'], '<')) {
        $transient->response['your-plugin/your-plugin.php'] = (object) array(
            'slug' => 'your-plugin',
            'new_version' => $update_data['version'],
            'package' => $update_data['download_url'],
            'url' => 'https://your-site.com'
        );
    }
    
    return $transient;
}

add_filter('pre_set_site_transient_update_plugins', 'check_for_updates');

Auto-Update System

Where Updates Are Stored

On your seller site, store plugin ZIPs in a releases/ folder:

plugin-files/
  your-plugin/
    releases/
      your-plugin-v1.0.1.zip
      your-plugin-v1.0.2.zip
      your-plugin-v1.0.3.zip  ← Latest version

The server plugin automatically finds the highest version number in this folder.

Releasing a New Version

Database Schema

FluentCart Pro Tables Used

wp_fc_licenses

CREATE TABLE `wp_fc_licenses` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `license_key` varchar(255) NOT NULL,
  `status` varchar(50) DEFAULT 'inactive',
  `limit` int(11) DEFAULT 0,
  `activation_count` int(11) DEFAULT 0,
  `expiration_date` datetime DEFAULT NULL,
  `product_id` bigint(20) unsigned,
  `created_at` datetime DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `license_key` (`license_key`)
);

wp_fct_license_sites

CREATE TABLE `wp_fct_license_sites` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `site_url` varchar(255) NOT NULL,  -- CRITICAL: 'site_url' not 'url'
  `created_at` datetime DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `site_url` (`site_url`)
);

wp_fct_license_activations

CREATE TABLE `wp_fct_license_activations` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `license_id` bigint(20) unsigned NOT NULL,
  `site_id` bigint(20) unsigned NOT NULL,
  `status` varchar(50) DEFAULT 'active',
  `created_at` datetime DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `license_id` (`license_id`),
  KEY `site_id` (`site_id`)
);

Testing Checklist

Deployment

Initial Setup (One-Time)

Success Criteria

The system is working correctly when all of these are true:

• Customers can purchase licenses on your seller site
• Licenses are created with status=’inactive’
• Customers can activate licenses on their sites
• First activation changes license status to ‘active’
• Activation limits are enforced
• Daily license checks run successfully
• Update notifications appear in WordPress admin
• Updates download and install automatically
• License remains active after updates
• Deactivation frees up activation slot

Key Takeaways

Security Considerations