The LicenseAcquirer property can be used as you would do for a standard MediaElement.
However, it can only be accessed through the ActiveMediaPlugin property of the player, which is a protected property.
So you need to subclass the SMFPlayer class, and then use this subclass as the player in the XAML.
class SMFLAPlayer :
var licenseAcquirer = ActiveMediaPlugin.LicenseAcquirer;