Is it possible to develop an free application that have some packages in it and those packages will have fee?

I want to develop an application for iPad. This will be free application. But in the application, t开发者_如何学运维here will be packages which will have cost. The user, who download the free version, could buy these packages from the application, not AppStore. I mean of course Apple takes %30 of the price but I want an application that some part of it is free, some with fee. Is this possible? or should I have to develop two different applications (one free application and one paid application)?

Have a look on In App Purchase feature.