You get cash back credited to your account with this card. You do not get a voucher like the Costco True Earnings card. Amex Blue can be a great deal for a cash card. I have had one for years. If you have $600.00 in the account you must keep it until one month past your anniversary date, the cash back is credited, and then use the card until your credit is done.

You should check out the T&C on the website. It appears to me that if you cancel the card you are out of luck.