Last year, Blizzard announced their intention to close the Diablo III real-money auction house. On March 18th of this year, Blizzard mostly completed that task and removed players' ability to bid, buyout, and list items on that auction house. However, since then, players have still been able to claim gold and receive items from the "Completed" auction house tab. They will remain able to do so until next week, in order to allow adequate time for players to retrieve anything they may have won or sold.
On June 24th, the shutdown of the Diablo III real-money auction house will be complete, and the real-money auction house will be gone in its entirety. Any items or gold that may be yours will be lost forever, so if you have any of these things lingering in what remains of the Diablo III auction house, now is the time to claim them.