You could some how check the date of the first "INIT" of your OCX vs. what the current date is using the registry to store the first date. Then after a certain period has expired you could disable some features. Or display an annoying message somehow

OR This next way...But it is in opposition of what you stated in your post about "working with full resources."

Let's say i download your OCX. And it has a property: SerNum
I go about using your OCX. BUT in those methods or whatever that you decide to "lock out" your code checks to see that I put the SerNum property equal to a certain string, lets say CB109F45. Now when I call a method that is locked down ,and I haven't put in the SerNum string, the method just simply exits itself.

This of course forces the developers to license it. Just lock out the useful methods/functions/events. This is however not a very "safe" way to do this. Because I'm sure people would share the codes or just hack the OCX to find out what the SerNum string should equal.

Well anyway I hope all this info helps.