In the rare occurrence you made a successful purchase, but the item doesn't unlock ( e.g. a map pack or premium IAP ) try the following steps.
1) Restart the app.
2) If this doesn't work, go to the settings page, and scroll down to the bottom and click the restore purchases button
3) If restore purchases fails, then just make the purchase again. If the purchase was successful the first time, you will not be charged a second time for the item. Go through the steps and you will be presented with a screen similar to the below
Click Buy again then you will see:
1) Restart The App
Android automatically unlocks any purchases made on your Google Play account on app start. If for any reason this does fail, then please send us a ticket, along with your receipt number so we can resolve.