The license is assocated with a system ID. You won't be able to just transfer a file on the system. You'll need to contact support to get a new license keyed to your new system ID. If you upgraded the existing system, I think the 5.x licenses will keep working.
From memory, the system keeps working with unlicensed modules, but those modules don't work and you'll get warnings. I would recommend undeploying them.