Issues with app installation
In some cases when you try to re-install Vimu app (after Factory reset, for example), Google Play Store MAY ask to buy the app second time. That's an issue with Play Store, not Vimu app.
What you can do:
Just try again later. Usually that helps..
Use PC version of Google Play (web site) and install Vimu app from there.
Try to "Buy" the app second time. Google will refund you any duplicate payment automatically.
Re-login to your Google Account on the device.
If nothing helps, try contacting Google Play support.
Please, note, that if you uninstall the app shortly after first install, Google Play will make you refund automatically.