Example of including a subscription's start date & end date in the customer new order email.

email-order-items.php

<?php
/**
 * Email Order Items
 *
 * @author     	WooThemes
 * @package 	WooCommerce/Templates/Emails
 * @version     2.0.3
 */

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

global $woocommerce;

foreach ($items as $item) :

	// Get/prep product data
	$_product = $order->get_product_from_item( $item );
	$item_meta = new WC_Order_Item_Meta( $item['item_meta'] );
	$image = ($show_image) ? '<img src="'. current(wp_get_attachment_image_src( get_post_thumbnail_id( $_product->id ), 'thumbnail')) .'" alt="Product Image" height="'.$image_size[1].'" width="'.$image_size[0].'" style="vertical-align:middle; margin-right: 10px;" />' : '';

	?>
	<tr>
		<td style="text-align:left; vertical-align:middle; border: 1px solid #eee; word-wrap:break-word;"><?php

			// Show title/image etc
			echo 	apply_filters( 'woocommerce_order_product_image', $image, $_product, $show_image);

			// Product name
			echo 	apply_filters( 'woocommerce_order_product_title', $item['name'], $_product );

			// SKU
			echo 	($show_sku && $_product->get_sku()) ? ' (#' . $_product->get_sku() . ')' : '';

			// File URLs
			if ( $show_download_links && $_product->exists() && $_product->is_downloadable() ) {

				$download_file_urls = $order->get_downloadable_file_urls( $item['product_id'], $item['variation_id'], $item );

				$i = 0;

				foreach ( $download_file_urls as $file_url => $download_file_url ) {
					echo '<br/><small>';

					$filename = woocommerce_get_filename_from_url( $file_url );

					if ( count( $download_file_urls ) > 1 ) {
						echo sprintf( __('Download %d:', 'woocommerce' ), $i + 1 );
					} elseif ( $i == 0 )
						echo __( 'Download:', 'woocommerce' );

					echo ' <a href="' . $download_file_url . '" target="_blank">' . $filename . '</a></small>';

					$i++;
				}
			}

			// Variation
			echo 	($item_meta->meta) ? '<br/><small>' . nl2br( $item_meta->display( true, true ) ) . '</small>' : '';

            <?php if ( WC_Subscriptions_Order::is_item_subscription( $order, $item ) ) : ?>
                <?php $subscription = WC_Subscriptions_Manager::get_subscription( $order->user_id, WC_Subscriptions_Manager::get_subscription_key( $order->id ) ); ?>
            	<p><?php echo __( 'Start Date: ' ) . date_i18n( woocommerce_date_format(), strtotime( $subscription['start_date'] ) ); ?></p>
	        <p><?php echo __( 'End Date: ' ) . date_i18n( woocommerce_date_format(), strtotime( $subscription['end_date'] ) ); ?></p>
            <?php endif; ?>

		?></td>
		<td style="text-align:left; vertical-align:middle; border: 1px solid #eee;"><?php echo $item['qty'] ;?></td>
		<td style="text-align:left; vertical-align:middle; border: 1px solid #eee;"><?php echo $order->get_formatted_line_subtotal( $item ); ?></td>
	</tr>

	<?php if ($show_purchase_note && $purchase_note = get_post_meta( $_product->id, '_purchase_note', true)) : ?>
		<tr>
			<td colspan="3" style="text-align:left; vertical-align:middle; border: 1px solid #eee;"><?php echo apply_filters('the_content', $purchase_note); ?></td>
		</tr>
	<?php endif; ?>

<?php endforeach; ?>