Protection from virtual machines

I'm writing a program and want to protect it by associating a hardware id. Ho开发者_JS百科wever, virtual machines can be cloned.

How do I know whether the program is running in a virtual machine? Are there any methods that determine what a program run through virtualization?

Detect virtualized OS from an application? is a related SO question that has a lot of relevant answers to what you are looking for.

A solution that has been somewhat effective is to use the permanent MAC address. Cloning this on a cloud-based VM is quite a nuisance.

It is probably better to offload this to 3rd party license servers.