Grammar help with "seem"

Both are possible. They have rather different meanings.

"They seemed to like my house." At some time in the past they appeared to like the house; perhaps that time was when they were actually in the house, and made complimentary remarks about it. It is possible, but cannot be deduced from the sentence, that they don't seem to like the house any more.

"They seem to have liked my house." At some time, or times, in the past, they liked the house. This belief (indicated by "they seem to have liked") is still current (though whether or not the house is still liked cannot be deduced).