You could enable measurements in the app for different time periods. During the time period you have unlimited amount of measurements. After the period has ended you have access to the saved measurements on the phone and the web (arboreal.se/forest).

You could buy usage for the following time-periods i Sweden:

24 hours – 50 kr (SEK)

14 days – 249 kr (SEK)

365 days – 3195 kr (SEK)

The price in USD is near (could be be difference between countries)

24 hours -$ 4.99 

14 days – $ 23.99

365 days –  $ 299