There are a variety of different types of houses and they also have different requirements to acquire them. For example, the inn room you get for free from the “A Friend in Need” quest, it can hold 15 furnishings, 1 trophy bust and 1 mount, pet or assistant. You can also purchase the other two rooms in the inn from the other alliances for 3000 gold. All the limits in your houses double once you have an active subscription to ESO.