Must buy them back which means you pay the tax (if any). Since the town center is, in fact, a local market but globally monitored, you must buy them back at the very fief you put them in.
Town centers are like the market place of cRPG : anyone can put an offer, and anyone can come and accept it... it can be useful in some circumstances but it is pretty under-used. The taxes are really important when using a town center. I think a 1% tax fief would be a good way to create a "storage" if everyone has enough gold, but then people could come and "rob".
Also if you are lazy and dont want to sell your S&D yourself, you can try to sell your goods at a price that the buyer would still have a benefit if he sell them again very far. If the global S&D is pretty low town centers could be useful
