Does Visual Studio have built-in tools for creating trial versions of software? If no what tools can do the job?
What are the best practices for creating trial versions on .NET platform?
How these practices depend on application type (web applications, Windows Forms applications, dll ect.)?
This is covered very well in the Shareware Starter Kit. It has code for limited trials, secure activation, registration and Paypal integration. Highly recommended, you don't want to invent that wheel.
The link I gave you is not a great one, you have to click through the license to get to the download. I can't find a link anymore that describes the C# specific version of that kit.