Hey Pooran,
First time when the app runs, it can be made to run trial without key for 30 days. If user requests we can grant extension for predefined days. If user wishes to pay and activate, we generate key and he can activate it. Am I right so far?
Yes.
1. Can this be achieved using only one product license?
Yes.
2. Can we activate the product for one year. And he should pay to reactivate.