When the Android™ device has established Wi-Fi or cellular connection, you simply synchronise your data. This is sending the data captured on the device over to the Machine Sentry servers which contain all the historical data of your site.
External web connectivity to the sensor is not required other than Bluetooth® to connect to the sensor from the Android™ device.
Data is only stored on the device with the free licence. To utilise all the benefits of Machine Sentry® you need a licence.