I bought my 6s Plus just last week and had basically the same thing happen to me. When I bought the iPhone, the employee at the Apple Store tried to migrate my data from my HTC One using the Move to iOS app, but for whatever reason, the connection between the iPhone and my HTC using the app would fail time after time, so I was unable to do the transfer. After wasting a lot of time trying to make the app work, I eventually told the Apple Store employee to just set up the phone as new.
After about a day of using the my new iPhone I decided to try using the Move to iOS app again and see if it would work this time (I had read on these forums that turning on airplane mode would solve the problem). So I proceeded to use Erase All Content and Settings to reset the phone and try using the Move to iOS app during initial setup.
Of course, the Move to iOS app still didn't work--the connection between the HTC and iPhone would keep dropping. After trying to get the phones to connect a couple more times I finally gave up and decided to setup the iPhone as a new phone again.
What I discovered was that after doing the Erase All Content and Settings procedure to reset the iPhone, the pre-installed apps that akram16 is describing (GarageBand, Keynote, Pages, etc.) were no longer on the phone. Apparently they're included out of the box, but once you do Erase All Content and Settings, they get erased. In my case however, I was lucky because they were already associated with my Apple ID (since I had installed them before on my iPad a couple of years ago) so all I had to do was reinstall them from the App Store.
akram16, you're not the only one who has this issue of them not being free on the App Store. I believe I read a couple of threads on the forums here (while I was researching why the apps disappeared when doing the phone reset), where a couple of other users also discovered that they were being asked to pay for the apps. I believe this may warrant a call to Apple, because the apps should indeed be free to install for you as a new iPhone user.