That information is not stored anywhere.
Upon enabling our "Licensing" support, a .DLL is automatically embedded in the project. That .DLL file does the verification of when the license has expired and prompts the user to activate the license.
However, the installation date is stored in the registries, if that helps. Having the installation date and the trial period, the .DLL file will calculate how many days are left until the trial will be done and then, after it is done, will prompt the user to activate it.
Hope this helps.