You should only have to pay once to use the questions. The game needs to be online to verify you have bought the questions, but once it has done that, it should be stored locally and you should not need to be online each time you play to use them.
Try the following fixes;
- Make sure your device is online (can you visit web pages in a browser?)
- Make sure you are signed into the Play Store with the same account that your used to buy the pack (you can check by running the Play Store and tapping on the shopping bag icon in the top left).
- Restart the app by going to Settings->App(lication)s find the app in the list and tap on it, then tap on "Force Stop", then start the game again as normal.
- If the questions are still locked, clear the data for the Play Store by going to Settings->App(lication)s->Play Store, tap on "Force Stop" then "Clear Data", and then try the steps above again.
The
Google download troubleshooter might have additional things to try.