And that's exactly my point! Twitterific should have known that Twitter could pull the rug out from under them at any time, and had a plan to make their customers whole in that eventuality.

Look, I'm not saying a company in their position should have to refund a one-time purchase cost of the app itself (for companies that do that sort of thing). But if you are charging an ongoing subscription for continuing service, and then that service terminates before the end of the subscription period, I think a pro-rated refund is more than fair.

Hell, if Twitter themselves charged a subscription fee for having a Twitter account, I would expect them to give pro-rated refunds to customers if they decided to wind down their business or pivot to something else. Twitterific should be no different here.