There are lots of concepts here for this blog post so I wanted to explain it in tiny bits....[Network licensing & Suites]....
Subscription + 3 versions back
When the licenses are on Subscripton that means that your license will support the current version and 3 versions back. This can be confirmed using the license parser.
Example of a license file that is on Subscription and not on Subscription http://upandready.typepad.com/up_and_ready/2012/10/understanding-licenses-on-subscription-and-not-on-subscription.html
Requesting a license that is paste 3 versions. It will look like a license that is not on Subscription. http://upandready.typepad.com/up_and_ready/2014/01/previous-use-license-request-running-software-that-is-more-than-3-versions-back.html
License parser limitations. Don't combine a 2014 license with a 2013 license that is on Subcription. http://upandready.typepad.com/up_and_ready/2013/11/license-parser-limitations.html
For example, if you have the Autodesk Product Design Suite Premium, I would start using the 2014 version if possible because it now includes Inventor Professional.
Because Inventor Professional 2013 was not included in the Autodesk Product Design Suite Premium 2013, you will not get the Professional features when running Inventor 2013.
The cascading sequences for the 2013 and 2014 product lines:
The features available between the Inventor family of products:
Network License Count
If you run the same version of the software in the Suite, it will use 1 license. This means that you can run AutoCAD Mechanical 2014, Inventor Professional 2014 and Mudbox 2014 on the SAME computer and it will only use only 1 license in your pool of network of licenses.
Search for How do network licenses for Suites differ from individual product network licenses?
This can can a bit tricky if you are running older versions of the software. If we use the license parser to check the license file for the Autodesk Product Design Suite Premium 2014, you will notice some older licenses (Feature codes) are indeed listed.
For example, looking at the highlighted sections (red underline), this means that you can run Inventor 2011 and AutoCAD Electrical 2011. You will notice that the Feature codes are separate and this will cause it to use 2 licenses. The reason for this behaviour is because the Product Design Suite did not exist in 2011. Please check out License Consumption noted here: