How do I enforce an expiration date for a trial install of my software?

I need to offer a trial period for my custom software. I have a 64-bit C# app, which uses 64-bit, multi-processor support DLLs. Other utilities to be included are written in C++ (exes and dlls). I must be able to encrypt the C# code, key the software to run only on a particular machine, and enforce an expiration date that cannot be foiled by resetting the machine clock.

I've evaluated several open source and COTS solutions: Infralution Licensing System, Protector, and ExeShield just to name a few. None of them satisfy all of my constraints.

Is anyone aware of an all-ecompasing solution that I should consider? Or do I need to do some registry diving and enforce it through custom code?