Booked by that date:
Your air travel can be taken after the expiration date as long as the credit is applied toward a new booking prior to the expiration date.
https://www.jetblue.com/help/travel-bank-credits
To be completely fair, I am sure I could e-mail them and get them to extend it another couple months given the current situation (which I will do if there are no takers), but I'd rather just sell it to someone who could use it and be done with it.