I think what people are objecting to here is that they are paying a lot of money for software and then feel like they are being blackmailed into spending more money otherwise they have completely wasted their initial investment.
When I purchased the software I believed that it would work in a similar fashion to antivirus software...you
can pay for future updates, but if you didn't then the software would still work, though there might be problems/errors and the ranks might be 'off' slightly.
What you are selling is basically not a software package...you are selling a licence to a product which happens to have an extremely high price tag for the first six months. As a customer, you receive nothing extra for that initial investment price as it stops working after 6 months...it's an extortionate price for a six month licence.
If I had realised that everything would stop when the live plan ended and I would not be able to use the software at all there is no way I would have purchased the entire suite. I would have purchased rank tracker on it's own and been
happy to pay the live plan subscription for it. Now I feel extremely cheated.
Personally I would like to see one of two things...either allow the software to work with the algorithms it currently has at the end of the live plan, and let the user know that some of the details might be out of date.
Or
I would like a refund for everything bar the rank tracker and I will purchase a live plan for that.
I think that something that ought to be considered is that we are all in the SEO game here, and if people start getting fed up with a company and start complaining there are going to be a lot of unhappy customers saying such on their websites and those websites are all going to be optimized using some sort of software. The best way to get customers is word-of-mouth and you can guarantee that's going to be the fastest way to lose potential customers too

If you are going to follow the licence plan that you are currently running then you need to only charge the licence fee for the first 6 months too, not the hundreds of dollars that leads you to believing you are actually 'buying' something.
One other thing to consider....a lot of people on the Internet do stuff for free. I'm not saying you have to give people something for nothing, but that is the way a lot of companies do business...give people something and allow them to 'donate' what they think it's worth. (We have a restaurant near us that works on the same principal and the manager says they rake it in...people pay far more because they have a conscience than they would if there were a bill presented to them)...just somthing to think about. I pay several companies a yearly subscription even though I don't have to, just because I
want them to succeed and keep doing business...and I know I am not the only one.