HomerJ,
The licensing are specific to all versions prior to ALM 11.52. Since ALM 11.52, the licenses have all been backward compatible. What this means is that as long as your license is valid and was issued for ALM 11.52 or later versions, you are free to upgrade to the latest version and migrate that license to the new version. Of course it goes without saying that the prior version must then be retired as the license can't be used for two separate production environments.

If you have an older version, such as ALM 11 or QC 9/10, then those versions are only valid for the version they were issued for and you will need to request a new ALM version license.

Hope this helps,
Dan Dailey