I have seen some apps like "Get paid to play" and "Appdog" were tapjoy is used. You do commercial campains and get paid for it.I was wondering if there was any way to use tapjoy in your app with your own point system. And if you reach a certain number of points, you will be able to get a pro or a paid version for free.
Are there any way of doing this?
Have you looked at Tapjoy's Knowledge Center? There's an article on managing your own virtual currency: Non-Managed Currency. It's entirely up to the developer how they intend to manage their virtual economy and what they offer for purchase. I don't know about converting virtual currency into a tangible good (like a Pro version) but you could certainly offer user's some in-game item that could reduce the number of ads they see.