I've had good success in the past with the Aladdin tools. It's a pretty cool setup you can define time limited trials, manage licenses that have very fine grained capabilities. Works splendidly with a Prism style composite app where you can enable individual modules for a license. A really cool feature is the usb dongle that allows you to store parts of your app on the key's storage itself. They were recently purchased by another company called safenet. But it's pretty much the same model as before.