How to retrieve a device ID like Mac Address to unique identify similar to Android or iOS

Hi, 

We are developing a Garmin Watch App in MonkeyC. We would like to uniquely identify difference watches of the same model who so ever is running our App. We tried to get Id following way - 

`var mySettings = System.getDeviceSettings();
var deviceId = mySettings.partNumber;
var id = mySettings.uniqueIdentifier;`

But, this id seems to be changing everytime we create a new build. 

Any insights here will be appreciated. 

Thanks