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 softw…
Software was never truly a "product" in the same way that physical goods are -- it was always a service thanks to the maintenance and continued investment required. It may have been better for the consumer in the short term to "buy" software, but a subscription model allows for more predictable cash flows to the developer of the software (which keeps software vendors in business -- and their software supported).