If you let your Autodesk Software Subscription lapse (expire) you need to be aware of your obligation to remove older versions of software from your computer.
An excerpt from the Autodesk License Agreement:
http://download.autodesk.com/us/FY16/Suites/LSA/en-US/lsa.html
1.2 Upgrades and Previous Versions
…any Previous Version will terminate one hundred twenty (120) days after Installation of the Upgrade.
The license to any previous versions are actually terminated. If you neglect to remove the older versions you most likely are in violation of the license agreement. If license compliance is not your job please let your IT staff know about this.