Software used means the software has already been used and that, after its first use, it is put back on the market. More than the software itself, in this area of importance the right to use a program, then the activation key rather than the DVD / CD or the Software in Physical Media.
The Software Used can come from multiple sources, but usually come from companies that have changed their systems or have updated existing ones or by companies that have bought stock in several Key and give away those excess (although they have never been used , they are still sold as used, since they have a change of ownership)
Buy Software Used takes advantage of the economic, because in the end there is an identical product and running the new, but with prices much lower.
The Court of Justice of the European Union (ECJ) has ruled on 3 July 2012 that trade in computer programs used is in principle legitimate. The ECJ ruled that the trade of software used is also permissible if it is software transferred online.
"In exchange for a payment, the user enters into a licensing agreement, through which the user gets the same perpetual right to use that copy, the copyright owner has sold the copy to the user and then runs his right exclusive distribution. "
With such business ownership is transferred to the copy itself.
The Software Used Disposable are also called for the principle of the rights of copyright:
The Software Directive in force in the EU provides for the mandatory nature of the application software to the principle of exhaustion of rights. This means that, from the time when the developer has sold for the first time a specimen of a program, his right to the further spread of such a copy is extinguished. As the author has already received remuneration for his work, he can not control the further distribution and even prohibit the resale. This applies to the software provided online, both for software sold on a data carrier. This is what was decided by the Court of Justice of the European Union in its judgment of 3 July 2012.
So ultimately if you buy a used software you can not sell and there is a risk that if you turn on multiple machines (or replace their own) code can be locked by the Software House, because the activation of multiple machines can make it look like the code as "pirate" having already had a propretario previously.
This here is the link to the Press Release 94/12 inherent in the grounds of the judgment in the case C128 / 11