The data storage format is slightly different in iOS and Android, currently it is not possible to sync or migrate data between iOS and Android directly.
iOS and Android device can be synced via our web version. It is a subscription based service as we need to store data on our server hosted on Microsoft Azure, and convert the data structure on the server.
By the way, if you just want to convert data once, the trial should be good enough. You do not need to subscribe after converting data. You just need to log off from those devices.
Please always backup ATracker data before data migration.