All the instructions for registering Poseidon are reported here: http://www.platon42.de/poseidonreg.html
You can fill the form also from the prefs in MorphOS.

I didn't think there were still this many people unregistered: Chris work is great, and so is his support. When 3.3 got released, without any limit for the Pegasos onboard chipset and even no annoying requester, I got even more impressed. And also the decision to let the MorphOS user decide how much Poseidon is worth to him, is something I really think should be rewarded. I decided to pay the upgrade fee (15 Euro) IIRC, because Posedon 2.x was somewhat registered for us. But I might chip in some additional money if I'll get upgrades in the future.
In the end I'd suggest everybody to register to Poseidon ASAP, regardless of the fact you're going to use a PCI USB2 controller or not. It's worth it, Chris deserves it, and shame on those who won't do it.

Kind regards,
Andrea