MM3D charts are licensed to the machine by System Id. The charts belong to that system/unit. When you sell your old unit, you should list it as part of the value being sold and price it accordingly. You might also consider the age of your licensed charts. If they are say version 1 and the current version is 4, the value is about half because it will cost the new owner half of list price to update his charts to the current version.
Predicting your next question (or someone else’s...)
There is the ability to move your chart license(s), IF your unit were to break and never return to service. This is done when a unit is condemned by our service center. When the license is moved, the broken unit is taken out of service. If someone were to do the “transfer” by mistake; the new owner of the old unit would NEVER be able to purchase charts EVER. This is because the old System Id is invalidated or locked out of the system for life. Only an authorized dealer or the factory service center can condemn a broken unit.
The charts have no value to a new purchaser, as they are of S. America, etc. They have value to me. Seems like they should be some provision put in place for this. It would make loyal customers happier and give me more reason to purchase a new Furuno MFD. I am going to put in a support request related to this, as I also have the issue with my Maxsea TZ, which uses the current charts and can be moved -- ah, but how will the charts go with it when it is associated with the new MFD?
Your case is unique in the manner that you have a “Cross License Agreement” with your MaxSea TZ Explorer and your NN3D. (Good news for you) You would need to provide our tech support your MaxSea TZ license number so that the "Chart License Link" can be broken with your old MFD. Your MaxSea TZ Explorer will retain the license(s) to your purchased charts. Once you purchase your new MFD, the TZ Explorer software can be "Linked" to it, and then your new MFD will be granted those same charts. The version of the charts granted, will be the same as you originally purchased.