Technically, it has to be paid by you. Only once was this actually ever an issue for me when once staying with a friend, they checked in before me and somehow they put the stay on their card at the end of the stay. It did not give me credit but in the end I was able to get it fixed. I cannot imagine using your spouse's card would be an issue though, especially if you stay together. Given that many spouses have AU cards from the other (even if you say you do not), there are just too many common reasons to use each other's cards where you still basically are paying that I cannot see it being an issue.