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Provided their policy hasn't changed, you can read this.

EDIT: Just saw you said "in app," so I'm not sure if that's actually the same thing.
 
Is it possible to ask for refund in app purchased that i didn't like?

thanks

Go into the iTunes Store on your computer, then click on your Apple ID on the top left corner.

In the Account Information page, scroll down to your Purchase History.

Click on the arrow pointing to the date you purchased the app, and then click "Report a Problem", and then click again on "Report a Problem" next to the app you're having an issue with.

Select the problem, fill out your comment, and then submit.
 
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