'terms' => array('subscriptions'),

'terms' => array('simple'),

<div class="prod-group-options">
    <p class="title">Select Your Product</p>
    <p>filter products</p>

    <ul class="produc-list">
        <?php //<form class="cart" method="post" enctype='multipart/form-data'>*/ ?>
            <?php
                $product_type = apply_filters(
                    'prod_type', array(
                        'taxonomy'  => 'product_type',
                        'field'     => 'name',
                        'terms'     => array('subscriptions'),
                        )
                );
                $quantites_required = false;
                $previous_post      = $post;
                $count = 0;
                foreach ( $grouped_products as $grouped_product ) {
                    $post_object        = get_post( $grouped_product->get_id() );
                    $quantites_required = $quantites_required || ( $grouped_product->is_purchasable() && ! $grouped_product->has_options() );
                    setup_postdata( $post =& $post_object );
            ?>
                <li id="product-<?php the_ID(); ?>" <?php post_class(); ?>>

                    <div class="prod-name">
                        <div class="radio">
                            <input type="checkbox" id="product-<?php echo $grouped_product->get_id(); ?>" name="<?php echo esc_attr( 'quantity[' . $grouped_product->get_id() . ']' ); ?>" value="1" class="wc-grouped-product-add-to-cart-checkbox js-group-item-sel"<?php echo ($count != 0 ? '' : ' checked="checked"'); ?> />
                            <label for="product-<?php echo $grouped_product->get_id(); ?>">
                                <?php echo get_the_title($grouped_product->get_id()); ?>
                            </label>
                        </div>
                    </div>
                    <?php
                    $product_price = $grouped_product->get_price();
                    if (empty($product_price)) {
                        $product_price = 0;
                    }
                    ?>
                    <div class="prod-price" data-price="<?php echo number_format($product_price, 2); ?>" data-contact-url="<?php echo esc_url( add_query_arg( 'subject', 'Purchase Enquiry: ' . $grouped_product->get_title(), site_url( '/purchase-enquiry-form' ) ) ); ?>">
                        <?php do_action( 'woocommerce_grouped_product_list_before_price', $grouped_product ); ?>
                        <?php
                            if ($product_price > 0) {
                                echo $grouped_product->get_price_html();
                            }
                            else {
                                echo 'On request';
                            }

                            echo wc_get_stock_html( $grouped_product );
                        ?>
                    </div>

</ul>