My understanding.
You cannot transfer your Sonar license to anyone else. If you have any prepaid membership time left after the move to a lifetime upgrade membership, the price of your upgrade to lifetime
should have been reduced in order to compensate you for that loss. People who had renewed their membership at the Cakewalk Store after purchasing a second year got a substantial reduction in price compared to users who had not upgraded until the lifetime option was offered. Other than that, I do not know of any way you can get a refund on unused membership.