message: Updates plan ID reference
diff: ) Free version
  option(
  - value='premium_monthly'
  - selected= (customer.get('plan_id') === 'premium_monthly') ? 'selected' : null
  + value='monthly_premium'
  + selected= (customer.get('plan_id') === 'monthly_premium') ? 'selected' : null
  ) Premium $5 / month
  option(
  