Years ago you could sell older software versions after buying a newer version. Even if the older version was used to get a discount on a newer version, it was still doable. For example, if I had ACME Software 2.x and I used its license to purchase ACME Software 3.x, I could sell my old ACME Software 2.x but it could no longer be used as a discounted upgrade path because I had already used it as such. I had to make it clear to the buyer that my old ACME Software 2.x was a "dead end" license, that is it could not be used for upgrades. To some people that is perfectly acceptable. It will be much less expensive to buy a dead end ACME Software 2.x license than to buy a new ACME Software 3.x license. And even with upgrade paths it might still be less expensive a couple years down the road to then buy a dead end ACME Software 3.x license after ACME Software 4.x has been released. And it will almost always be less if you wait and buy every other just out dated release. Let's face it, not all software newest releases are worth updating to and some folks would be perfectly happy to be one release behind.