You don't. Those users helped bootstrap the company; you deliver the service at the level you promised as long as you're able to. If you didn't promise free up

You don't. Those users helped bootstrap the company; you deliver the service at the level you promised as long as you're able to. If you didn't promise free updates/upgrades, you then can sell additional premium services only available to people who voluntarily upgrade to a package that pays more. The very least that a company that wants to go back on the promise would have to do would be full refunds. It would still be wrong, but the fact that they aren't even giving those out (automatically on cancellation, without asking) shows the lack of good faith.