You can review your purchase history through the following steps:
ANDROID
- On your device, open the Google Play Store app.
- Press Menu > Account > Purchase history.
- Choose a specific entry to see the corresponding receipt.
iOS
- Go to the iTunes Store and App Store, then tap on your ID > View Apple ID.
- At the bottom you will find "Purchase history".
- There you will be able to see all the purchases made, both free and paid, in chronological order.