You will lose them. The tickets will require to you pick a start date and they will only be valid for a few days after that start date (they give you more than 5 days to redeem but it depends on if you buy a 5d or 6d etc). If you use the ticket at all (even only 1 day), the terms indicate it's no longer refundable. ONLY if you never use it at all.
"Tickets are nonrefundable. After expiration date, the price paid for a wholly unused ticket can be applied to the purchase of a new ticket with an equal or higher price."