Alter subscription export CSV with Order / Coupon / Subscription Import Export Plugin for WooCommerce (https://www.webtoffee.com/product/order-import-export-plugin-for-woocommerce/)

functions.php

<?php // do not copy this line
add_filter('hf_alter_coupon_csv_header', 'wt_csv_subscription_add_more_columns', 10, 1);

function wt_csv_subscription_add_more_columns($csv_columns) {
    $csv_columns['meta:_stripe_source_id'] = 'meta:_stripe_source_id';
    $csv_columns['meta:_stripe_customer_id'] = 'meta:_stripe_customer_id';
    return $csv_columns;
}

add_filter('hf_alter_subscription_data', 'wt_csv_subscription_add_more_data', 10, 1);

function wt_csv_subscription_add_more_data($order_data) {
    $additional_meta['meta:_stripe_source_id'] = '_stripe_source_id';
    $additional_meta['meta:_stripe_customer_id'] = '_stripe_customer_id';
    foreach ($additional_meta as $key => $val) {
        $order_data[$key] = get_post_meta($order_data['subscription_id'], $val, TRUE);
    }
    return $order_data;
}