If you have activated a current license of ARES Commander, you can also use all previous product versions of ARES Commander with this activated license.

E.g. A valid ARES Commander 2015 license will run together with ARES Commander 2014, ARES Commander 2013, ...

Note:The activation with a product key works only with the correct ARES Commander product version. You can't activate in the previous product versions with a newer product key. (e.g. ARES Commander 2014 won't accept a product key from ARES Commander 2015)