I appreciate all of your replies but I don't think you're getting what your customers are saying here. I want to be clear that I've read the FAQ and I've read all your replies here thoroughly. I now fully understand the offer, but to others it may be unclear. As a fellow developer, I know we can be blind to user interpretation due to our deep knowledge of a product.
Also, I am not sure where you got the idea that you would be forfeiting your Fences3 license, as that is simply not true.
I said it's unclear whether that is the case as it is not defined anywhere. An upgrade may include the forfeiture of the original item so it was a concern. Thanks for clearing that up, you may want to add that to the FAQ.
I agree. It is clearly stated Single vs. Multi- device.
Also, if something is unclear nothing prevents one from making a forum post asking a question.
Problems come up because people make assumptions such as the thought that "I had 5 of Fences 3 so if I upgrade, I'm entitled to 5 of Fences 4." which ignores the actual offer. Version and number of licences are two different things altogether, hence the two separate prices: Having five bananas does not entitle one to five coconuts for the price of one. Any grocery store will tell you that.
It's not clear, that's what we're all saying. As a user, I don't even look at the SINGLE/MULTI-DEVICE wording; I see one upgrade button and I know I have an earlier version so that's all I'm clicking.
Making a forum post to ask a question before purchasing is horrible UX. The offer should be crystal clear without additional prompt. Where is the actual offer anyway? There's no clarity aside from the panel title.
I disagree that "version and number of licences are two different things", I have a Fences3 5 PC license and to me that is one thing. If someone sold me 5 bananas and then asked me if I'd like to upgrade to coconuts, I would expect (without further clarification) that I'm getting 5 coconuts (I'd also expect that I'm forfeiting the bananas). If you instead told me that I now have access to a discounted price on one coconut it would be more reflective of the offer.
That said, are you suggesting that this could be highlighted?

If you are truly interested in utmost transparency without additional bloat, I would put the change in license count behind the upgrade button. Simply change "Great, you qualify for a Fences® 4 upgrade discount." to "Great, you qualify for a Fences® 4 Single Device discount."
Again, I get it now, but it shouldn't have taken me a FAQ and 20 post forum thread to do so. I'm not the only customer in this thread that thinks so.