I paid for an iPhone app which is now free?

Is it possible to get a refund for an app you pay for that becomes free some time later? Eg whatsapp

I don't think so, unlucky.

Nope. You got use of the paid features while it was paid. There are probably still premium features that you have acess to that free users don't.

No, as you bought it when it cost. For example, if you bought a car, and traded it in later, you'd get less money than what you paid. With apps, they age and the market stops going down on them. Once the publisher doesn't make as much money as they originally did, the price is marked down.

I buy something last month in a shop
This week, they have it on discount/ have reduced the price,

Same situation.

You bought it at a price /did a deal that was 'acceptable' to you
(or you would not not have bought it)
-> contract and deal done and closed.

So no,
you don't get any money back
you get what you paid for.

Of course not, i paid for 100's of apps that are now free.

I'm afraid no the same thing happened to me unlucky