Nothing, provided you don't reset licenses too often. However any reading made in a device before reseting that haven't been exported to the cloud will no longer be able to be exporte, turning them useless.
You can use any device you want, as long as it is able to work with our application. To a better experience we recommend using a professional device or a normal device with a external Bluetooth scanner. It's possible to use the application without these, you can search for you items or use your phone camera to read the barcoode.