Hexels 2 and Hexels 3 licenses are assigned to the email address you specified at the time of purchase: your Marmoset ID. If you wish to move your license from one machine to another, simply install the appropriate version of Hexels on the new computer and log into the software using your Marmoset ID.
You will be asked for your email address – enter it, and follow the authorization link that arrives in your inbox. Once this is done, the new computer will be authorized. You may transfer your license as often as you like, even between OS X and Windows.