After referring to Dale's fine answer, something about licenses and copying:
You may have purchased an item with a license that allowed certain copies to be made. If you sell the item, the license now applies to the new owner. So unless the license says that you can keep copies even after a sale (which is unlikely with an item that is sold for profit), you will have to either destroy all copies made or hand them over to the new owner. You have no right to those copies anymore.
Also, if you agreed to license terms, then the new owner will have to agree to the exact same license terms. You can't circumvent licensing conditions by doing a resale. Basically, after X used the item for some time and then sells it to Y, the result should be exactly the same as if Y had bought the item in the first place.
To those who think it is horrible that the copyright owner might not get paid: When I buy anything, I look for value for money. The "value" includes my ability to recover some money by selling the item used. If I couldn't do that, the item would be worth less to me in the first place, and I wouln't buy it for that price.