Your nodelocked license key must be stored in a specific user directory, although this can be moved. These locations depend on your operating system and are shown below for a user called Fred.
Mac OS X
/Users/Fred/Library/Application Support/lightmap/licenses/hdrlightstudio.1851.2016.0413.lic
Windows
C:\Users\Fred\AppData\Local\lightmap\licenses\hdrlightstudio.1851.2016.0413.lic
Linux
/home/Fred/.local/share/lightmap/licenses/hdrlightstudio.1851.2016.0413.lic
If you have trouble navigating to these directories from your file browser (these directories are sometimes hidden), just run HDR Light Studio and launch the Preferences dialog. From here you can open the license directory.