To get the latest VERSION (2000i^2, 2001, etc) you have to be paid up on maintenance, then PTC should send you the disks automatically, or you can request them.
To get an updated BUILD CODE (or the revision releases of the same version), I don't know if you need maintenance, I don't think so, but you can also request those from PTC via their website.
Your license codes should be fine if your updating the BUILD CODE, but you have to call License management or go up on the web and get updates licenses if you are changing VERSIONS