David Kimura PRO said almost 4 years ago on Payment Gateway Basics with Stripe :
Stripe::Plan.create(
  { 
    product: { 
      name: 'Pro',               
      id: 'pro'
    }, 
    id: 'pro',
    interval: 'month', 
    currency: 'usd', 
    amount: 1500
  }
)

This is what I use to create the Product/Plan