When I was talking to Autodesk customer service, they said that if you cancel maintenance subscription, you go back to the original version of the software that you paid a perpetual license for. For example: if you have 3ds 2014, and you are on maintenance subscription and currently you are using 3ds 2016, if you cancel you will no longer be able to use 3ds 2016 but instead can only use 3ds 2014. They could have been wrong in what they told me, Customer service doesn’t always know everything about the terms of licenses, but it wouldn’t surprise me if it is truly that way.
If you’re on regular subscription (without paying for a perpetual license) then when you cancel you have nothing.