I agree: the word “Enterprise” with NethServer appeals to another context (BTW i think we must change that page, or replace it with the service we’re planning here).
As usual Proxmox web site is a source of inspiration: from their home “Get subscription” points to “Subscription plans”, where they states:
A Proxmox VE Subscription is an additional service program designed to help IT professionals and businesses to keep their Proxmox VE deployments up-to-date. It also provides access to professional support services: You get access to the Proxmox VE Enterprise repository with stable software updates and security enhancements, as well as to technical support and other services.
…it seems that “NethServer subscription (+plans?)” can work.