async function listSubscriptions(auth) {
  const service = google.reseller({version: 'v1', auth});
  const res = await service.subscriptions.list({
    maxResults: 10,
  });
  const subscriptions = res.data.subscriptions;
  if (!subscriptions || subscriptions.length === 0) {
    console.log('No subscriptions found.');
    return;
  }

  console.log('Subscriptions:');
  subscriptions.forEach(({customerId, skuId, plan}) => {
    console.log(`${customerId} (${skuId}, ${plan.planName})`);
  });
}
Lists the first 10 subscriptions you manage.

@param {google.auth.OAuth2} auth An authorized OAuth2 client.