The site is a "shareware" site for Psion and other PDAs.
You should have a trial period for the software you downloaded, and then be able to register your name/address and whatever other info if you decide to purchase it. Generally "registration codes" are obtained at the time of purchase by ordering the full version of the software through the website. ( http://www.rmrsoft.com/general/progtbl.htm )
There should be an option to bypass this screen and continue with the program (whichever one you downloaded). There may be a reminder screen that comes up until you register, but you should be someone operational on your download if it was a recent download and install -- but if the trial period has expired, and you still wish to use the software, then you will need to purchase a registration code.