if i were you i would hang on to it, your not going to get much for it anyway, and it is quite possible at sometime in the future you may want to make a return to sonar because of some as yet not seen reason, added features, improvements whatever, if that was the case you could be saving yourself money by holding on to it and perhaps getting a sweet upgrade price as apposed to paying the full price again. just as platinum is a whole step up from x3, the same may happen in the future where some update or new version raises the level again and hits it out of the park. i never sell anything (
have given away a few things that i inadvertently purchased multiple copies of . . . don't ask ;) . . . . ) but i prefer to keep stuff.
if you are set on trying to sell it, legalities aside, (
and i am no lawyer but i believe in some places the not to be resold part of eula's are considered invalid) you could try kvr's 'sell and buy' sub forum, you often see sonar/cakewalk stuff for sale there, however they are usually whole user accounts, i guess you could just set up a new email, attach it to your account, remove/change any personal info from your account etc, they do it quite often. but as i said if i were you i would hold on to it, could save you in the long run, and not much harm done if it doesn't.