diff --git a/omnisend/class-omnisend-core-bootstrap.php b/omnisend/class-omnisend-core-bootstrap.php
index f45976d..f83a64b 100644
--- a/omnisend/class-omnisend-core-bootstrap.php
+++ b/omnisend/class-omnisend-core-bootstrap.php
@@ -20,10 +20,14 @@
 
 defined( 'ABSPATH' ) || exit;
 
+define( 'OMNISEND_CORE_PLUGIN_VERSION', '1.0.0' );
 define( 'OMNISEND_CORE_SETTINGS_PAGE', 'omnisend' );
 define( 'OMNISEND_CORE_PLUGIN_NAME', 'Omnisend Core' );
 define( 'OMNISEND_CORE_WOOCOMMERCE_PLUGIN_NAME', 'Email Marketing for WooCommerce by Omnisend' );
-define( 'OMNISEND_CORE_API_V3', 'https://api.omnisend.com/v3' );
+
+// Change for different environment.
+define( 'OMNISEND_CORE_API_V3', 'https://api.omnisend.com/v3' ); // todo do not commit.
+define( 'OMNISEND_CORE_SNIPPET_URL', 'https://omnisnippet1.com/inshop/launcher-v2.js' );
 
 require_once 'module/class-omnisend-core-connection.php';
 require_once 'module/class-omnisend-core-options.php';
diff --git a/omnisend/module/class-omnisend-core-connection.php b/omnisend/module/class-omnisend-core-connection.php
index 30bb772..2dbbb17 100644
--- a/omnisend/module/class-omnisend-core-connection.php
+++ b/omnisend/module/class-omnisend-core-connection.php
@@ -10,19 +10,30 @@
 class Omnisend_Core_Connection {
 
 	public static function display() {
-		if ( ! empty( $_POST['action'] ) && 'connect' == $_POST['action'] && ! empty( $_POST['api_key'] ) && ! Omnisend_Core_Options::get_api_key() ) {
+		$connected = Omnisend_Core_Options::is_store_connected();
+
+		if ( ! $connected && ! empty( $_POST['action'] ) && 'connect' == $_POST['action'] && ! empty( $_POST['api_key'] ) ) {
 			check_admin_referer( 'connect' );
 			$api_key  = sanitize_text_field( wp_unslash( $_POST['api_key'] ) );
 			$brand_id = self::get_brand_id( $api_key );
 			if ( $brand_id ) {
+				// Set credentials so snippet can be added for snippet verification.
 				Omnisend_Core_Options::set_api_key( $api_key );
 				Omnisend_Core_Options::set_brand_id( $brand_id );
-			} else {
+
+				$connected = self::connect_store( $api_key );
+				if ( $connected ) {
+					Omnisend_Core_Options::set_store_connected();
+				}
+			}
+
+			if ( ! $connected ) {
+				Omnisend_Core_Options::disconnect(); // Store was not connected, clean up.
 				echo '<div class="notice notice-error"><p>API key is not valid</p></div>';
 			}
 		}
 
-		if ( Omnisend_Core_Options::get_api_key() ) {
+		if ( $connected ) {
 			echo 'You are connected to Omnisend!';
 			return;
 		}
@@ -51,4 +62,45 @@ private static function get_brand_id( $api_key ): string {
 
 		return is_array( $arr ) && ! empty( $arr['brandID'] ) && is_string( $arr['brandID'] ) ? $arr['brandID'] : '';
 	}
+
+	private static function connect_store( $api_key ): bool {
+		$data = array(
+			'website'         => site_url(),
+			'platform'        => 'api',
+			'version'         => OMNISEND_CORE_PLUGIN_VERSION,
+			'webserver'       => 'Wordpress: Omnisend Core Plugin',
+			'phpVersion'      => phpversion(),
+			'platformVersion' => get_bloginfo( 'version' ),
+		);
+
+		$response = wp_remote_post(
+			OMNISEND_CORE_API_V3 . '/accounts',
+			array(
+				'body'    => wp_json_encode( $data ),
+				'headers' => array(
+					'Content-Type' => 'application/json',
+					'X-API-Key'    => $api_key,
+				),
+				'timeout' => 10,
+			)
+		);
+
+		if ( is_wp_error( $response ) ) {
+			return false;
+		}
+
+		$http_code = wp_remote_retrieve_response_code( $response );
+		if ( $http_code >= 400 ) {
+			return false;
+		}
+
+		$body = wp_remote_retrieve_body( $response );
+		if ( ! $body ) {
+			return false;
+		}
+
+		$arr = json_decode( $body, true );
+
+		return ! empty( $arr['verified'] );
+	}
 }
diff --git a/omnisend/module/class-omnisend-core-options.php b/omnisend/module/class-omnisend-core-options.php
index 793e290..3c1f7a8 100644
--- a/omnisend/module/class-omnisend-core-options.php
+++ b/omnisend/module/class-omnisend-core-options.php
@@ -9,8 +9,9 @@
 
 class Omnisend_Core_Options {
 
-	private const OPTION_API_KEY  = 'omnisend_core_api_key';
-	private const OPTION_BRAND_ID = 'omnisend_core_brand_id';
+	private const OPTION_API_KEY         = 'omnisend_core_api_key';
+	private const OPTION_BRAND_ID        = 'omnisend_core_brand_id';
+	private const OPTION_STORE_CONNECTED = 'omnisend_core_store_connected';
 
 	public static function get_api_key(): string {
 		$api_key = get_option( self::OPTION_API_KEY );
@@ -39,4 +40,18 @@ public static function set_brand_id( $brand_id ): bool {
 
 		return update_option( self::OPTION_BRAND_ID, $brand_id );
 	}
+
+	public static function set_store_connected(): bool {
+		return update_option( self::OPTION_STORE_CONNECTED, true );
+	}
+
+	public static function is_store_connected(): bool {
+		return boolval( get_option( self::OPTION_STORE_CONNECTED ) );
+	}
+
+	public static function disconnect() {
+		delete_option( self::OPTION_API_KEY );
+		delete_option( self::OPTION_BRAND_ID );
+		delete_option( self::OPTION_STORE_CONNECTED );
+	}
 }
diff --git a/omnisend/module/view/snippet.html b/omnisend/module/view/snippet.html
index c7f7b7e..41bbaad 100644
--- a/omnisend/module/view/snippet.html
+++ b/omnisend/module/view/snippet.html
@@ -4,7 +4,7 @@
     omnisend.push(["track", "$pageViewed"]);
     !function(){var e=document.createElement("script");
         e.type="text/javascript",e.async=!0,
-            e.src="https://omnisnippet1.com/inshop/launcher-v2.js";
+            e.src="<?php echo OMNISEND_CORE_SNIPPET_URL; ?>";
         var t=document.getElementsByTagName("script")[0];
         t.parentNode.insertBefore(e,t)}();
 </script>