Your CalMAN license is permanent and never-ending. You can continue using your purchased version of CalMAN forever at no additional cost. 

Initial purchases of CalMAN include free software updates and technical support for one year.  At the end of that year, you can renew your All Access for CalMAN to continue to receive the latest CalMAN updates and continued technical support. You can purchase an All Access one-year renewal from the SpectraCal online store.

When you start the installation of CalMAN v5.3 or newer, you will see a maintenance information dialog that tells you whether maintenance is current for your CalMAN license. If your maintenance is not current, you can continue to run your original version of CalMAN, but you will be unable to install the current CalMAN version.