Discount codes can be applied to a subscription to activate a promotion.
If set the discout code will auto select this plan
The unique code that can be applied to a checkout
Whether the discount code has already expired.
ID to identify the discount code with
The max usage of this discount code
ID of the promotion that is attached to the discount code
Whether the discount code can be redeemed. Returns true only if related Discount is activated and Discount code has not expired.