diff --git a/includes/api/src/Package.php b/includes/api/src/Package.php
index 1f2ba8b8f07..05cda53a193 100644
--- a/includes/api/src/Package.php
+++ b/includes/api/src/Package.php
@@ -1,5 +1,7 @@
 <?php
 /**
+ * Deprecated notice: This class is deprecated as of version 4.5.0. WooCommerce API is now part of core and not packaged seperately.
+ *
  * Returns information about the package and handles init.
  *
  * @package Automattic/WooCommerce/RestApi
@@ -11,38 +13,48 @@ defined( 'ABSPATH' ) || exit;
 
 /**
  * Main package class.
+ *
+ * @deprecated Use \Automattic\WooCommerce\RestApi\Server directly.
  */
 class Package {
 
 	/**
 	 * Version.
 	 *
+	 * @deprecated since 4.5.0. This tracks WooCommerce version now.
 	 * @var string
 	 */
 	const VERSION = WC_VERSION;
 
 	/**
 	 * Init the package - load the REST API Server class.
+	 *
+	 * @deprecated since 4.5.0. Directly call Automattic\WooCommerce\RestApi\Server::instance()->init()
 	 */
 	public static function init() {
+		wc_deprecated_function( 'Automattic\WooCommerce\RestApi\Server::instance()->init()', '4.5.0' );
 		\Automattic\WooCommerce\RestApi\Server::instance()->init();
 	}
 
 	/**
 	 * Return the version of the package.
 	 *
+	 * @deprecated since 4.5.0. This tracks WooCommerce version now.
 	 * @return string
 	 */
 	public static function get_version() {
-		return self::VERSION;
+		wc_deprecated_function( 'WC()->version', '4.5.0' );
+		return WC()->version;
 	}
 
 	/**
 	 * Return the path to the package.
 	 *
+	 * @deprecated since 4.5.0. Directly call Automattic\WooCommerce\RestApi\Server::get_path()
 	 * @return string
 	 */
 	public static function get_path() {
-		return dirname( __DIR__ );
+		wc_deprecated_function( 'Automattic\WooCommerce\RestApi\Server::get_path()', '4.5.0' );
+		return \Automattic\WooCommerce\RestApi\Server::get_path();
 	}
 }
diff --git a/includes/api/src/Server.php b/includes/api/src/Server.php
index 1c589c0da75..4eb3384baa3 100644
--- a/includes/api/src/Server.php
+++ b/includes/api/src/Server.php
@@ -22,7 +22,7 @@ class Server {
 	 *
 	 * @var array
 	 */
-	protected $controllers = [];
+	protected $controllers = array();
 
 	/**
 	 * Hook into WordPress ready to init the REST API as needed.
@@ -51,11 +51,11 @@ class Server {
 	protected function get_rest_namespaces() {
 		return apply_filters(
 			'woocommerce_rest_api_get_rest_namespaces',
-			[
+			array(
 				'wc/v1' => $this->get_v1_controllers(),
 				'wc/v2' => $this->get_v2_controllers(),
 				'wc/v3' => $this->get_v3_controllers(),
-			]
+			)
 		);
 	}
 
@@ -65,7 +65,7 @@ class Server {
 	 * @return array
 	 */
 	protected function get_v1_controllers() {
-		return [
+		return array(
 			'coupons'                  => 'WC_REST_Coupons_V1_Controller',
 			'customer-downloads'       => 'WC_REST_Customer_Downloads_V1_Controller',
 			'customers'                => 'WC_REST_Customers_V1_Controller',
@@ -86,7 +86,7 @@ class Server {
 			'taxes'                    => 'WC_REST_Taxes_V1_Controller',
 			'webhooks'                 => 'WC_REST_Webhooks_V1_Controller',
 			'webhook-deliveries'       => 'WC_REST_Webhook_Deliveries_V1_Controller',
-		];
+		);
 	}
 
 	/**
@@ -95,7 +95,7 @@ class Server {
 	 * @return array
 	 */
 	protected function get_v2_controllers() {
-		return [
+		return array(
 			'coupons'                  => 'WC_REST_Coupons_V2_Controller',
 			'customer-downloads'       => 'WC_REST_Customer_Downloads_V2_Controller',
 			'customers'                => 'WC_REST_Customers_V2_Controller',
@@ -127,7 +127,7 @@ class Server {
 			'system-status-tools'      => 'WC_REST_System_Status_Tools_V2_Controller',
 			'shipping-methods'         => 'WC_REST_Shipping_Methods_V2_Controller',
 			'payment-gateways'         => 'WC_REST_Payment_Gateways_V2_Controller',
-		];
+		);
 	}
 
 	/**
@@ -136,7 +136,7 @@ class Server {
 	 * @return array
 	 */
 	protected function get_v3_controllers() {
-		return [
+		return array(
 			'coupons'                  => 'WC_REST_Coupons_Controller',
 			'customer-downloads'       => 'WC_REST_Customer_Downloads_Controller',
 			'customers'                => 'WC_REST_Customers_Controller',
@@ -176,6 +176,15 @@ class Server {
 			'data-continents'          => 'WC_REST_Data_Continents_Controller',
 			'data-countries'           => 'WC_REST_Data_Countries_Controller',
 			'data-currencies'          => 'WC_REST_Data_Currencies_Controller',
-		];
+		);
+	}
+
+	/**
+	 * Return the path to the package.
+	 *
+	 * @return string
+	 */
+	public static function get_path() {
+		return dirname( __DIR__ );
 	}
 }
diff --git a/includes/class-wc-api.php b/includes/class-wc-api.php
index 629e82feec1..5347b5f7499 100644
--- a/includes/class-wc-api.php
+++ b/includes/class-wc-api.php
@@ -39,6 +39,14 @@ class WC_API extends WC_Legacy_API {
 		if ( ! $this->is_rest_api_loaded() ) {
 			return null;
 		}
+		if ( method_exists( \Automattic\WooCommerce\RestApi\Server::class, 'get_path' ) ) {
+			$path = \Automattic\WooCommerce\RestApi\Server::get_path();
+			if ( 0 === strpos( $path, __DIR__ ) ) {
+				// We are loading API from included version.
+				return WC()->version;
+			}
+		}
+		// We are loading API from external plugin.
 		return \Automattic\WooCommerce\RestApi\Package::get_version();
 	}
 
@@ -52,7 +60,7 @@ class WC_API extends WC_Legacy_API {
 		if ( ! $this->is_rest_api_loaded() ) {
 			return null;
 		}
-		return \Automattic\WooCommerce\RestApi\Package::get_path();
+		return \Automattic\WooCommerce\RestApi\Server::get_path();
 	}
 
 	/**
@@ -62,7 +70,7 @@ class WC_API extends WC_Legacy_API {
 	 * @return boolean
 	 */
 	protected function is_rest_api_loaded() {
-		return class_exists( '\Automattic\WooCommerce\RestApi\Package', false );
+		return class_exists( '\Automattic\WooCommerce\RestApi\Server', false );
 	}
 
 	/**
diff --git a/includes/class-woocommerce.php b/includes/class-woocommerce.php
index 146376c31f2..9908924d103 100644
--- a/includes/class-woocommerce.php
+++ b/includes/class-woocommerce.php
@@ -303,7 +303,7 @@ final class WooCommerce {
 	 * Load REST API.
 	 */
 	public function load_rest_api() {
-		\Automattic\WooCommerce\RestApi\Package::init();
+		\Automattic\WooCommerce\RestApi\Server::instance()->init();
 	}
 
 	/**