Your Indiana motorcycle endorsement is valid for the period of validity of your driver’s license.
You may renew your motorcycle endorsement at any Indiana license branch up to two years before the license expires. If you are less than 18 years of age when you get your license, you must renew your license between your 21st birthday and no more than 30 days after your 21st birthday.
Additional information on renewal requirements is located at http://www.in.gov/bmv/2758.htm on myBMV.