There are three reasons to why this might happen:
1. You’re offline while trying to download the app, go online and try again.
2. Are you logged into the same Google Play account as you bought it from? If not, please log in and try again.
3. Try downloading the app while connected to either your network or wifi.
4. Make sure you're not logged into a restricted profile when downloading the app.
5. If nothing of these two helps and you're confident that you have purchased the app, please contact us at firstname.lastname@example.org.