WooCommerce - Custom meta data on the cart and checkout pages

<?php
// WooCommerce - Custom meta data on the cart and checkout pages

add_filter( 'woocommerce_get_item_data', 'tp_get_custom_item_data', 10, 2 );
function tp_get_custom_item_data( $item_data, $cart_item ) {
  if( isset( $cart_item['size'] ) ) {
    $item_data[] = array( 'name' => 'Size', 'value' => $cart_item['size'] );
  }
  return $item_data;
}

// add custom meta to order
add_action( 'woocommerce_new_order_item', 'tp_add_custom_meta_to_order', 99, 3 );
function tp_add_custom_meta_to_order( $item_id, $item, $order_id ) {
  if( !isset( $item->legacy_values ) ) { // applies to order_item_shipping
    return;
  }
  if( isset( $item->legacy_values['size'] ) ) {
    wc_add_order_item_meta( $item_id, 'Size', $item->legacy_values['size'] );
  }
} // end function