The ability of The Ulfberht Device resolves during each player's "choose a house" phase (Step 2), so it would first resolve during the turn after it enters play, and would prevent the player from choosing the house that they chose in a previous turn. The Ulfberht Device does not have to be in play to be aware of a previous game state, in this case the house chosen by a player in the previous turn.
For example: On turn 1, Player A chooses Dis as their active house. Player B chooses Star Alliance and plays The Ulfberht Device. On turn 2, Player A reaches Step 2, The Ulfberht Device resolves, and cannot choose Dis.
For example: On turn 1, Player A chooses Dis as their active house. Player B chooses Star Alliance and plays The Ulfberht Device. On turn 2, Player A reaches Step 2, The Ulfberht Device resolves, and cannot choose Dis.