Make expiry time optional

[Jon007]

Expiry time should be optional or a custom field on this product type.

Case 1:
When a customer is buying a gift for someone, they do not expect their gift voucher to expire unused after only a short amount of time.

Case 2:
If you are issues incentive or reward coupons as a gift (eg adding the 'gift coupon' product as a free bonus to the shopping basket) then yes it is appropriate to have a short expiry date