Good news! You OWN that housing deed! No monthly rent or subsidaries is required of you :)
You begin by being able to own 3 houses per each wizard. You may have more houses that you can buy with gold, Crowns, or from prepaid game cards. However, to own more than three will require you to purchase an "Additional Housing Elixir".
You may even put a single house with or without furniture (minus pets, mounts, and NO TRADE items) into your Shared Bank so one of your other wizards can have it. You can only have one in the Shared Bank at a time. Also that particular house will not be eligible to be shared again for 90 days.
Hello there! Once you purchase a castle in Wizard101, it is yours forever unless you decide to throw it away or sell it! Unlike real life, there are no monthly fees or subscriptions for castles in the game.