Is it necessary to have the app on whenever I use the scale?

You do not need to have the mobile app on while you use the scale.

When your app is off, data will be stored in the scale each time you measure, for up to 20 data sets. Then next time you open the mobile app and the app-to-scale connection is reestablished, all the previous data from all scale users will be uploaded to the app. If there is a difference of about 6 lb (3 kg) or more, or if there are significant changes in the data over a short period of time, the app will allow manual allocations of each data set to a correct user. This helps avoid mistakes in the automation. You are also allowed to delete data that don’t belong to any users.