Warehouse Keepers offer to store some items for you. You may store a great deal in the alloted 3 large tabs. However, an AP Item may be purchased to double your storage space for a period of 30 days (Honestly, it isn't worth it as one could just create multiple accounts). There is no fee for storing items, however, there is a 5% fee for retrieving them. Items in your Warehouse will be available to any character on your account.
Double Warehouse Edit
When you begin in Normal Mode, you can only use the first three of the six tabs in your warehouse.