If you want to learn about a really interesting aspect of the "first sale doctrine" and how it applies to software, you should have a look at "Vernor vs Autodesk" in the USA and compare it to "Oracle vs UsedSoft" in the EU. Basically, in the USA the courts determined that if a company sells you software, but in their terms & conditions claim that they are merely granting you a license, then you can't resell the software b/c you aren't considered to own it. In the EU however, if a company sells you a permanent life-time license in exchange for a one-time fee, the courts determined that you aren't merely licensing that software, you own it and you are allowed to resell it.
I think these different rulings haven't been fully appreciated yet. For example, if you buy Apple's Final Cut X for $299, you should be allowed to resell that software if you live in the EU, but there is currently no way to transfer licenses between users, preventing users from reselling it. It seems to me that by preventing users from reselling their software, Apple (and the Google Play Store) are probably violating EU law on this matter.
I think these different rulings haven't been fully appreciated yet. For example, if you buy Apple's Final Cut X for $299, you should be allowed to resell that software if you live in the EU, but there is currently no way to transfer licenses between users, preventing users from reselling it. It seems to me that by preventing users from reselling their software, Apple (and the Google Play Store) are probably violating EU law on this matter.