Here's the clause from the MPC Software installer, you know, the bit that everyone agrees to that no one ever actually reads
9.2. Transfer to third party. If you are the person who initially licensed the software, you may make a one-time permanent transfer of your license and the software to another end user, provided that you do not retain any copies of the software and you follow inMusic’s license transfer procedures. For further information, please visit the Web sites listed at the end of this document.
That sounds pretty clear to me - only the person who originally purchased the MPC gets to do a one time transfer to someone else. That means if you purchase second hand, you don't get to sell it on. In theory of course, I do suspect this is unlikely to be something they hold you to in practice, but do be aware that it is there in black and white.
I would also point out that clause 1 of the license claims it is a 'non transferrable' license, so the 9.2 clause is actually at odds with clause 1. The license also doesn't allow for you to use the software on more than 1 device at a time, yet we know the beta 'ilok' allows for installation and activation on 2 devices.
Of course, this is Akai we are talking about, so I assume the iconic tea boy put the license together on his lunch break.
BTW, on the subject of the license, if you intend using any of the supplied expansions in your music, be aware that you agree to "indemnify, defend, and hold inMusic harmless from and against any claims or liabilities arising from your use of the media elements". So if any of the sounds in those expansions have dubious copyright history and you get sued for using them, you cannot in turn sue inMusic for supplying them to you.
Also if you use those sounds, you must 'include a valid copyright notice on your derivative works' - to be pedantic, this means that if you wish to release public domain music (which has no copyright and therefore cannot include a copyright notice), you cannot use any of the supplied expansions to make that music.