I am talking with a client that currently is running a MX600 and has I think about 5 years of Adv Security Licensing remaining on it. If they wanted to buy a MX450 or MX250 to replace the MX600 does meraki have a way of downgrading the license to the MX450/250 or trading it in on the MX450/250 Lic.
I mean the MX650 5yr Adv Security lic is $105,000 and the MX450 is $66K so a straight downgrade to the MX450 or 250 would make sense for Meraki as they get you to buy the new hardware and obviously they already got your money for the License and it was significantly more than what you would have paid for the new hardware.
Now for the client the best case would be if it had a trade program where they got the credit for the amount they spent on the higher priced lic so that they would get more days on the new lower tier but I don't see that happening. I would just be happy if some way you could convert from a more expensive MX license to a cheaper one day for day at least.