gift token 
(also gift voucher)
noun British
A voucher given as a present which is exchangeable for goods.The King then presented me with a gift token of £2....
- You can imagine my delight when, later in the week, I was presented with a surprise gift voucher for a full aromatherapy treatment.
- I was presented with a lovely bouquet of flowers, given a gift voucher to spend and someone took me round the store in a wheelchair.