Don't show recurring price for WooCommerce subscriptions worth 0$

PHP Snippet 1:

add_filter('woocommerce_subscriptions_product_price_string', 'alter_woocommerce_subscriptions_product_price_string', 10, 3);

function alter_woocommerce_subscriptions_product_price_string($subscription_string, $product, $include) {
    if ($include['sign_up_fee']) {
        if (strpos($subscription_string, '0.00') !== false) {
            $subscription_string = explode('and a', $subscription_string);
            $subscription_string = $subscription_string[1];
        }
    }
    return $subscription_string;
}