In order to have a house you must have a treasury where you can store your
belongings. The treasury in your house is twofold. It allows you to store
items there that will save over reboots. The items in this treasury remain
there even when you are not in the game and are therefore subject to looting
if not sufficiently protected. The treasury also marks for code purposes
your house. It is stored in your player file. This allows mobiles you hire
to know where you live.
The shop storeroom is used to store goods you might have for sale. Anything
left in this storeroom will be sold. A shop keeper will buy items if you
tell them to so you can set up a trade system. Any shop-keepers hired will
proceed to your storeroom instead of your treasury so your shop storeroom
will need to have an exit into your shop. Note that containers and items
in containers cannot be sold in player run shops. Even if you elect to
have no shop, you are allocated a shop storeroom and it is part of your 10
room total.
Note that if you do not have a shop storeroom and hire a shopkeeper he will
sell stuff that is stored in your treasury.
Do not store carts or pets in your shop storeroom. It causes problems
with the game. This includes your own pets or carts and other characters
pets and carts.