I purchased tweetbot a long time ago and I have enjoyed this great app for a while. Now I got worried because my app didn't get the latest update and for some reason it's not part of my purchased apps anymore and when I go to the App Store it tells me that I have to pay again. Am I missing something here? Is the new app a new thing and I have to pay again or this is some kind of glitch and problem that is affecting only my account?
The App Store does not allow for "upgrade" pricing. So if the developer continues to update an existing app, the update is available to all who have the app, without additional cost. Of course, those updates are not "free" - they cost the developer time, effort, and sometimes they have to invest quite a bit of resources. In this case, the developer creates a new version (Tweetbot 3 vs Tweetbot 4)...
I have no problem paying for good software that I use regularly (daily/all day long). The developer deserves to be paid for their efforts. You may not like it, but this is how it works... and we all have to pay for things that we like/use/do.
I find it strange that people will pay $6 for a burger that fills them up one time, but want to complain about "having to" pay $4, $5 or $6 for an app that they use on a regular basis. The thing is, you
don't have to pay for the update. You are free to continue using Tweetbot 3 for the price that you paid to get it however long ago you got it. But if you want the new updates, you have to pay for them.