Hello,
About the "Essentials Plus" license, it's an economical package, gives you vCenter and three nodes (two CPU sockets each), so it;s about hosts, not a total of 6 CPUs, so you won;t be able to license a single host with more than two CPUs, even if you have only one physical server to license.
as long as you aren't interested in HA, just keep using the free edition, but the free edition has disadvantages, specially with other vendors, so you can't backup your VMs with Veeam or veritas unless you a fully licensed host.