Old version of Photoshop (3.0, 4.0, ... CS5 up to CS6) gave you a license key you could sell. It didn't include a time limit. It was yours and you could sell it or use it forever. That's gone.
You can try to find old licenses for CS6, sure, but at some point, but it's a very different purchase and licensing system from what they have now.
That's false. When one purchases a copy of a (book|software|video), one then owns that good.
A typical proprietary software licence text is irrelevant when it comes to terms of ownership, transfer of ownership, use of the good etc. as the law applies and determines "how [things] actually are". A contract, let alone a unilaterally dictated licence text, is legally unable to take away certain rights the consumer enjoys.
If you don't like it, keep using your old version under the old licence.