Android :: How Licensing Work In Transitioning From Free App To Paid?

Here's the scenario: The app is on the market for free. The publisher then decides to make it a pay app and changes the status. I'm assuming you can just do that, but my questions are:
1) Will the publishing console require us to upload a new version if it is to be a pay app, or can we just change it on-the-fly? 2) If we can change it on-the-fly, how will that affect users that have downloaded the free version? Do they get the license to the paid one as well (so they can delete but reinstall the app for free, get updates, etc?) I've finished a game but I've been just waiting for the paid apps to come on line before publishing it. I'm now thinking that I wouldn't mind a 1 week free period before going paid but something felt like the users who download it for free would never have to pay even after I change it to paid and add some sort of desirable update that makes them want to download the new version (and pay then to get it if they have to).