This feature applies to the Duxbury Braille Translator only. It is for users with a valid DBT license, perhaps purchased with an earlier version of the program.
"License for 45-Day Trial" gives you a place to enter your Duxbury License Text. From that day, it begins a 45-day period during which DBT will run in normal production mode without activation. At the end of that period you must activate your DBT for it to continue running.
If you entered your license during installation as most people do, there is no need to re-enter it here. The 45-day trial period does not restart.