Don't waste your money
I have free apps that do the same thing but better. UK we buy fuel by litres, but still quote Miles per gallon, this app can not convert to mpg. I have been running it alongside a free app with a similar name, and prefer the free app. Shame you can't get a refund for apps that don't do what you want or expect. Also on a paid for app I don't expect to have to work round adverts for other apps.