Can WinLicense protect stand alone DLLs that I would sell? Customers would just buy my DLL to integrate it with their own complete application.

You can protect DLLs normally as you do with applications (EXEs). You can put Trial or Registration options in your DLL.

You might want to protect your DLL to be executed *only* when a valid license is present in the directoy where your DLL is located. So, you have to activate Registration options before protecting your DLL (and mark the option "Application only runs when registered" if you want that your DLL only executes when it's registered with a valid license key).

You can also protect your DLL with Trial options, so, your DLL can run in Trial mode for a specific period or with options disabled.