This is not an error message. It just means exactly what it states, that you don't have a license so the server will shut down at some point because it's in trial mode.
I just ran into the same error on my local enviroment. It seems I was using a wrong backup file for the database. It gave this same error. Just info for people who run into the same problem :-)
then how do we use the trial version , when it is so limited .i just add a text box and the same error appears for version 8.6