The only way sensor data is lost is if you delete a sensor device. The FilesThruTheAir™ Cloud asks if you definitely want to delete the sensor so you will not be able to do this by mistake. If you have a Free account, the FilesThruTheAir™ Cloud stores only the most recent 45 days of data. Data older than this is automatically deleted.
! Please be aware that when you highlight a unit on the ‘Devices’ screen and then go to ‘View Data’, only the data from the latest ‘live’ data session will be displayed. You have to click on the ‘Other Sessions’ tab, which will then bring up a list of all the sessions for that device. Just highlight the session you want and click on Graph, Data or Summary to bring up the views for that particular data session.