At best this is an anti-consumer practice, regardless of how snotty you get about how "your EULA in 2011 said X" you have done very little to dispel any confusion about the license agreement - this thread is a testament to that - Telling users "it's buried in that long-since replaced EULA from 2011 (which we know you didn't read)" is not enough, you need to take steps to actively avoid any confusion or misrepresentation of your product - an email to existing users clarifying that this is the case as an example would have gone a long way.
I purchased a license in 2013 (rather than go down the piracy route) as I wanted to support the development of the product - I won't be supporting it further