stripe.js

const addApiIncrease = async (req, res, next) => {

  stripe.setApiVersion('2018-05-21');

  const billingId = req.account.billing.customer_id;

  const newSubscription = await stripe.subscriptions.create({
    customer: billingId,
    items: [
      {
        plan: 'api_141121_25',
        quantity: req.body.quantity
      }
    ]
  }).catch(err => {

    logger.error(err, req);

    return res.jsonp({
      error: err
    })
  })