Almost everyone knows that when you have an Autodesk product and it is on Subscription, you have access to use the current version and 3 versions back. i.e. AutoCAD 2013-2010. When a license is generated and it is on Subscription, it will have the SERVER lines, PACKAGE & INCREMENT codes in it.
If the license file is NOT on Subscription, it will only allow you to run the 'current' version only. When this license is generated, it will only have the SERVER lines & INCREMENT codes in it.
Using the license parser, you can quickly see what that means: