Couple questions: trialware and admin user

[Tom Redyns]

Hello,

I've been reading the NSIS and haven't quite found an answer to the following questions pertaining to my desktop installer. The questions are:

1. What type of NSIS strategy can I user to do a "15" day trialware installasion?

2. Upon reinstalling on the 20th day, still disallow the user to use the application until they purchase a license?

3. How do I mandate that the user installing my desktop application has administrator or administrator group acccess?

4. How do I ensure my installation allows all users for the desktop to use the application?

Thanks...Tom