If I have a customer who wants to buy 10 years support license up front and NOT have to plug-in codes, or files after initial deployment? Looking to deploy to a air gapped site customer does not want shutdown to occur due to license expiration.
AFAIK when/if the license expires - it will not shutdown your operations, the updates will be blocked and some annoying messages friendly reminders will appear.
It's not a license (to run it) but a subscription (for support). It will keep running, and you can get updates, but you do not get personalized support (without a subscription that gives you support tickets).
To be even more pedantic, the subscription, depending on the level, will give access to the enterprise repository. Which we definitely recommend for production environments. And then, depending on the level, can also include support tickets.
The license of our products is primarily the AGPLv3.
But as @bbgeek17 mentioned, these questions are best handled by either a local partner or our shop team.
The tool intended for these air-gapped use-cases is the Proxmox Offline Mirror https://pom.proxmox.com/ which will cover the subscription key activation and mirroring the enterprise repo to make it available to the air-gapped systems.