A voucher: a coupon or document used as proof for payment or exchange for services or goods (loanword from English).
旅行会社からホテルのバウチャーがメールで届いた。
I received the hotel's voucher by email from the travel agency.
このバウチャーをレジで提示すれば割引が受けられます。
If you present this voucher at the register, you can get a discount.
返金の代わりに店舗で使えるバウチャーを受け取った。
Instead of a refund, I received a voucher usable at the store.