How to use AddressesToLocationsAsync method?

[HubertLo]

From the sample code in the sample project, I know how to use AddressToLocationsAsync to do geocode one address at a time. However when I am looking at the documentation, I notice this AddressesToLocationsAsync method:
http://resources.arcgis.com/en/help/silverlight-api/apiref/api_start.htm?ESRI.ArcGIS.Client~ESRI.Arc...
ESRI.ArcGIS.Client.Tasks Namespace > Locator Class : AddressesToLocationsAsync Method

My questions are:
- Is this call requires me to have the annual subscription to the geocoding service?
- Does anybody has some sample codes for this call?