Yes Jasen - I had read that elsewhere in this thread and until today I wasn't aware of that. But I'm not sure how exactly that would work. How does VSL know what licenses are on dongle that failed? I have two dongles that I purchased in 2015, but I can't look up the serial number of when I registered them and VSL would have no clue what (if anything) I had on them.
Go to MyVSL. In the upper left hand side select MyProducts. Along the top you will see three items, "Software," "Instruments" and "ViennaKey/elicenser." I think the Software and Instruments are selected by default so select the ViennaKey/elicenser and scroll all the way down. There you should see all of your keys when they were registered and their serial numbers.
As to which licenses each key is holding Steinberg may have a record of that because you have to go on to their site in order to enter the activation codes.
I understand your "spread the risk" strategy but you might want to rethink it because it would be a real pain trying to keep six different keys up to warranty.