This was brought up recently on debian-legal: it is unclear what the licensing conditions of Transity are. Specifically, it appears that you are violating the terms of your own license.
It's fairly clear that GPL-3+ is the licence you are distributing the code under: its is what's listed in you description. However, you add the additional condition that long-term users purchase a license. That is not a legal request to make of GPL-3+ licensed code: the GPL explicitly prohibits additional restrictions. Granted, you could be choosing to distribute your code under a new license that is based on the GPL, but in that case, you would need to comply with a few additional rules (which you don't), and other projects would be unable to use your code as part of their software (defeating the point of the open-source system).
In short, you can't require your end users to do much of anything, or place restrictions on the redistribution of your code, without violating the terms of the GPL. As soon as a person owns software covered by the GPL, they have the ability to use, modify, and redistribute it as they please: even if you say in the README that they have to purchase a license, they don't: they already have one.
Fear not, however: there is an easy solution to permit you to distribute your code as GPL3+ while also requesting donations and prohibiting commercial redistribution. Simply rephrase your additional line that requires that long-term users purchase a license to one that asks for donations, and uses the currently existing price as a recommended donation. That would let Transity be included in debian, which would also cause Transity to be distributed as part of Ubuntu, Mint, and almost any other distro that isn't Arch or Fedora.
Its worth noting that you keep the ability to sell a commercial license to Transity, no matter what solution you pick. You can also chose to stop offering your code under the GPL altogether, and simply have it exist as a source-available paid software product (whose source is copyrighted and may not be redistributed) or even just as a standard proprietary software application. You could even distribute the GPL'd source only to those who buy your product. The thing you can't do is give people GPL'd code, then ask them to give you money later.