One click check out plugin

Hi
i was looking to buy one click checkout plugin- had some question to get started

1) WHat is the difference between free and paid versions – in features if can compare before i use
2) Does this subscription come with lifetime updates from my dashboard
3) DO you have any prevailing discounts available
4) I need 3 licenses – is there a discount for quantity
5) Can i change the website and cancel it from particular website and reinstall in another in future incase required