I got my NY ferret/fitch-ferret/fitch owner/breeder license six years ago,
and it's been a yearly renewal at least that long.  In fact, since ferrets
were regulated in NY (to prevent illegal rabbit hunts, way back when) it's
always been necessary to renew it every year.
 
The Dept. of Environmental Conservation should be sending you a renewal
notice every year, about a month or so before your current license expires.
About they only time it'll ever be checked is if you buy or sell ferrets,
though.
 
E.S., Hershey and Nestle'
[Posted in FML issue 1183]