- If the refund is done within a 48 hour time window of the in-app purchase;
- All the original items from the purchase are still owned by the user
If the conditions are met, here is how to request a refund from Steam. On your Steam client, visit your account details -> purchase history -> choose the item that you would like to refund -> choose "I would like a Refund".
Purchases of Items outside of the game from in steam work a bit differently. These are considered DLC and must be refunded using the normal steam method. You can find directions for that here: https://store.steampowered.com/steam_refunds/