I've noticed this 60 month limit on Meraki Now as well. I would reach out to your distribution Cisco team to see if they know of anyway to extend it.
Things I would consider:
Maybe you can buy 2x 60 month SKU's in advance? Maybe you can charge your customer for 120 months now and then order the back 60 months with your distributor 5 years in advance (or remember to renew before 5 years). I know, kind of odd ideas, but there is always a way when $ is involved, right?
- Ex community all-star (⌐⊙_⊙)