I don't think it was mentioned above (I might have missed it - and it may not apply to this situation), but just to point out that the licensing of Sonar does not allow sale or transfer to anybody, and when the initial install is done there are two explicit check boxes that spell that out, and are required to be checked to indicate acceptance and understanding of that in order to proceed with the installation.
Cakewalk has been super kind to actually rely on trust for the above, since they began, and as posted above by others, the current sale prices are so low that someone should be able to get a fantastic product with whatever level of X3 that they can afford.
Bob Bone