tiers element represents a pricing tier in your product.
The tier model
Use it to define each pricing tier individually.
If your product doesn't have tiers, it's a single-tier product. Set
unit_amount when you charge per unit. For example, "User based pricing", $10/user.
flat_amount when you charge one total cost for a given subscription, for example, "Premium plan", that has prices for $20/month, $200/year.
|Yes||Per unit price for units relevant to the tier.|
|Yes||Price for the entire tier.|
|Yes||Up to and including to this quantity will be contained in the tier.|