Tracking purchases with Google Analytics and Facebook for Freemius Checkout

freemius-checkout-ga-fb-tracking.js

//
// Gist was kindly contributed by @jamesckemp from @iconicwp. Thanks!
//
handler.open({
  ...
  
  purchaseCompleted: function( response ) {
      var trial = response.purchase.trial_ends !== null,
          total = trial ? 0 : response.purchase.initial_amount.toString(),
          productName = 'Product Name',
          storeUrl = 'https://your-site.com',
          storeName = 'Store Name';

      if ( typeof fbq !== "undefined" ) {
          fbq( 'track', 'Purchase', { currency: 'USD', value: response.purchase.initial_amount } );
      }

      if ( typeof ga !== "undefined" ) {
          ga( 'send', 'event', 'plugin', 'purchase', productName, response.purchase.initial_amount.toString() );

          ga( 'require', 'ecommerce' );

          ga( 'ecommerce:addTransaction', {
              'id': response.purchase.id.toString(), // Transaction ID. Required.
              'affiliation': storeName, // Affiliation or store name.
              'revenue': total, // Grand Total.
              'shipping': '0', // Shipping.
              'tax': '0' // Tax.
          } );

          ga( 'ecommerce:addItem', {
              'id': response.purchase.id.toString(), // Transaction ID. Required.
              'name': productName, // Product name. Required.
              'sku': response.purchase.plan_id.toString(), // SKU/code.
              'category': 'Plugin', // Category or variation.
              'price': response.purchase.initial_amount.toString(), // Unit price.
              'quantity': '1' // Quantity.
          } );

          ga( 'ecommerce:send' );

          ga( 'send', {
              hitType: 'pageview',
              page: '/purchase-completed/',
              location: storeUrl + '/purchase-completed/'
          } );
      }
  },
  
  ...
});

@vovafeldman
Please where to add in plugin and how to add a custom script or a tracking pixel?
Sales tracking is very essential for good PPC marketing.