In Maryland, Once you have a Motorcycle Licence, it's good for life. Which may or may not be a good thing. For instance, I have mine, and the last Motorcycle I owned or rode was in 1980 !
Oh, the licenses you get are for life here, too. Two ways to lose them: Traffic violations (i.e. speeding or drunk driving) or being determined medically unfit.
For speeding you normally only lose it temporarily, though. Repeat offenders may be forced to re-take the test, though.