I have an app with paid content, and I want to offer it for free, with tapjoy offerwall. So when a user wants to buy an item, my app will ask him “buy it or get it for free?”.
My question is: Google will allow this? Or can remove my app?
It’s totally OK to do that
Thanks for your answer 
It’s ok to use both. Even I am using them
Thanks, I’m going to do it then 
Well, it’s a bit tricky… What do you mean by
Is that actually free? or you mean they have to fill out the Tapjoy offers to get some coins and then unlock some features in your app… In this case, it violates the GP rule.
Ads | Android Developers
If your app uses adwalls to drive affiliate traffic, those adwalls must not force the user to click on ads or submit personal information for advertising purposes before using the app.
Forcing a user action in an adwall is not only a poor user experience, it is a violation of Google Play policies.
SO, it means you need to integrate Tapjoy, or any other coin-based system in a smart way. Like giving daily rewards, or make to play the game without pushing them to buy or click on ads.
At the end, there are a million of apps/games that violates GP policy but they still live and making money. It’s just your destiny if they will catch you or not.
Well, I’m a bit confused now… so it’s not allowed by Google?
My app has 2 extra features that, so far, the user can buy. Now each feature will have the option to get for free using tapjoy offerwall too.
So, each feature will have 2 buttons: “buy” and “get for free”.
It isn’t allowed?
EDIT: I readed your link. I think Google will allow what I’m doing, because I’m not forcing the user to do it. The user can use my app without those extra features, or buy it with real money.
I also feel it should not be a problem - if the Tapjoy stuff is not restricting anything, but giving MORE options to the user.
For example user is already restricted in that they have to buy with IAP to get some extra feature. If you ALSO give them an additional way to unlock it with Tapjoy, then you are not restricting them further with Tapjoy addition. So it should not be a problem.
But you have to be careful about the language you use - lest it be confusing to someone from Google.
Try to use language which suggests the Tapjoy addition is in ADDITION to what you already offer in the app.
I don’t know about the appropriateness of an app which essentially prevents users from proceeding until they do IAP - ideally even with IAP, the user should have a way of progressing (perhaps harder but still possible) without using IAP.
But in the case of IAP, Google may give that leeway - I am not sure about whether time-limited apps are allowed or not ?
That is, once you offer an app for free - then I think ideally it should be usable without having to do Tapjoy i.e. user should not be prevented completely from proceeding further.
That certainly applies to Tapjoy etc. - whether that applies to IAP also I am not sure.
I think you misinterpreted that clause, it says you can’t force users to click ads in order to use your app. As in “click this admob banner to advance to new level”
Well, this is what I wanted to say. And @adforandroidapps, did better then me.
The point behind my words was, to do not FORCE users to fill Tapjoy offers, because it is even horrible then just to click on ads. It’s all about the force. Users should be able to play your game/app without purchasing via IAP/Tapjoy/etc…
If your app/game is free, then it should be free. The OP said, they can use his app even without these features, so I believe he is in safe side.