Pay now versus pay at the property
A large share of listings here are booked without payment and settled at the desk on arrival. For those, there is no online transaction for credit to apply to — the hotel takes the money directly.
Only prepaid bookings can use credit. That is a real restriction and it narrows the choice considerably, especially in some countries where pay-at-property is the norm.
Tell the recipient to filter for prepaid rates or the credit will sit there while they book the way they always have.
Region and currency
Country-specific, and the currency has to line up with the account. Prices are often displayed in a currency chosen by the user, which is not the same as the account's billing currency — check the billing one.
Genius levels and discounts
The platform's loyalty discounts reduce the price, and credit pays what remains. They do not conflict.
Taxes and city charges
Local tourist taxes are frequently collected at the property regardless of how the room was paid for. Those will not come out of credit, so the recipient should expect a small bill at the desk even on a prepaid stay.
Who it suits
Someone with a trip already planned who books hotels rather than apartments. Weaker as a speculative gift, because unused travel credit tends to expire unspent.
Asking for one
Country, currency, amount. Background in the travel guide.