Beginning June 1st, we will be removing support for previous MB 2 Supporter keys in the MB 3 Server and removing this field from the product.
As long as you get your MB 2 key in before this date, you will get credit for any MB 2 registrations. After that time, it won't be possible to enter the old key and the system will stop checking against the old database.
We aren't making this move to try and take anything away but the old MB 2 database is being shut down and we want to remove this additional complexity from the current product. The need for this field should be very small at this point so it is just a point of confusion for new users going forward.
So, if you've been dragging your feet on making the move over to MB 3, I suggest you go ahead and do it .