If you want to buy the downloadable version of Universalis instead of reading it free on the web, the world has until now been divided into two halves: the iPhone/iPod Touch, and everything else. This is because the iPhone version is sold by Apple and doesn't require registration codes, while the other versions are sold by us and do use registration codes. The consequence was that if you wanted to have Universalis on (say) both your iPhone and your Mac, you had to pay twice; which was manifestly unfair.
It has been difficult to break through this "Apple Curtain", but we have now done it - in one direction, at least. If you have Universalis on the iPhone, this can now generate a registration code that will activate Universalis on your other computers.
For this to work, you need to have the latest version (1.29) of Universalis on the iPhone, and the latest versions (now available on our web site) of the software for your other systems. http://www.universalis.com/n-download.htm is the place to start: it has links to the specific pages for each kind of computer that Universalis works on.
You still can't move in the other direction. That is, if you have a registration code for (say) the Mac, you'll still have to pay again if you want to have Universalis on your iPhone. We're looking into ways round this as well, but it all depends on Apple's policies.