And even then (let's say 2008), if you purchased the most expensive license (Enterprise processor license) and paid for all sockets (it was calculated per socket, not per core) you could run as many SQL Server instances with as many users as you wanted on that server, in however many VMs you needed. No subscription, permanent license. You might have to purchase support extensions if you wanted ability to call MS for issues, but that's separate thing and you can ignore it if you don't need it.