For use with fixed expiration date subscriptions (not End Date). Typically only possible while using an AutomateWoo workflow. This will add a new line in the cart if the $product_id is present, displaying when the subscription will expire.

wcs_add_cart_first_renewal_payment_date_EXP.php

<?php

function wcs_add_cart_first_renewal_payment_date_EXP( $order_total_html, $cart ) {
    
    $product_id = '19';
    $product_cart_id = WC()->cart->generate_cart_id( $product_id );
    $in_cart = WC()->cart->find_product_in_cart( $product_cart_id );
    
    $title_exp = get_the_title( $product_id );
	if ( 0 !== $cart->next_payment_date ) {
        	if ( $in_cart ) { 
            		$expiration_date = 'December 31, 2019';
            		// translators: placeholder is a date
            		$order_total_html  .= '<div class="first-expiration-date"><small>' . sprintf( __( '<br><hr>Subscription containing <strong>%s</strong> will expire on: %s', 'woocommerce-subscriptions' ), $title_exp, $expiration_date ) .  '</small></div>';
            
        	}
    	}
	return $order_total_html;
    
}
add_filter( 'wcs_cart_totals_order_total_html', 'wcs_add_cart_first_renewal_payment_date_EXP', 99, 2 );