As the above articles describe, Twitter have recently begun enforcing a maximum number of accounts that 3rd party clients such as ourselves are able to serve. Tweetro recently hit this limit and can no longer be distributed.
In an effort to continue providing this service, we've opted to pull Tweetro from the store and relaunch it as a paid app (Tweetro+).
Had these restrictions not been imposed on us, we'd be more than happy to continue distributing the app freely as the exposure we've received from doing so has been amazing. Unfortunately, the circumstances have forced us to put a price tag on it to justify ongoing development. Of course, these restrictions also apply to Tweetro+ meaning we'll only ever be able to distribute it to a limited number of people.
We truly apologize for the inconvenience and hope you'll continue supporting us as we strive to deliver the best possible Twitter experience on Windows 8.
If you have any further questions or comments, please don't hesitate to get in touch with us via @tweetroapp or email.