Hello!
You might use the following SKU C9200-LIC= to upgrade the current subscription. If it is a brownfield deployment, you can use the C9200-DNA-A-48= instead.
If customers choose to upgrade (first SKU), they get credit for the remaining term of the current Essentials Subscription (if the subscription is still active, of course).
Hope it helps!
Orlando González .:I:..:I:.