From Hobbyist Software
Most registration codes entitle you to free upgrades for a year. Details on the upgrade policy are here
You can tell when your registration code expires from the last 6 digits. E.g. the code 12345-200810 expires on the 10th month of 2008.
When your code expires, you can continue to use versions of the applications that were released before the expiry for as long as you like.
Alternatively, if you log in to your account then you can purchase an upgrade at a discounted rate. (Please make sure that you don't turn scripts off in your browser as this will hide the discount gadget).