Woocommerce change/update user role on product purchase

The below function provides a feature to change the user’s role in the purchase of a product in WooCommerce. The example function will change the existing ‘Subscriber’ to the role of ‘Customer’.

function change_users_role_on_purchase( $order_id ) {

    $order = new WC_Order( $order_id );
    $items = $order->get_items();

    foreach ( $items as $item ) {
        $product_name = $item['name'];
        $product_id = $item['product_id'];
        $product_variation_id = $item['variation_id'];

        if ( $order->user_id > 0 && $product_id == '222' ) {
            update_user_meta( $order->user_id, 'paying_customer', 1 );
            $user = new WP_User( $order->user_id );

            // Remove role
            $user->remove_role( 'subscriber' ); 

            // Add new role
            $user->add_role( 'customer' );
        }
    }
}

add_action( 'woocommerce_order_status_processing', 'change_users_role_on_purchase' );