TBH, the resale value of software is usually very low. Particularly so when upgrades are needed to ensure compatibility with current systems.
For example, I recently advertised a Maxim iLok license on eBay. Here in the UK, it retails new at GBP £288. I couldn't shift it at any price ! ! !
You might be lucky and find someone who wants v4 for a legacy system. However, with the rise in popularity of Melodyne, it's not going to be an easy ride and the value will reflect this.
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