When you start the application for the first time, it will enter in Member Mode. You can change this mode to enter Administrator Mode. At this time, a new window will appear asking you to set up a password. You can go back to the program's main menu after clicking on Administrator Mode again.
If you don't know the password, then simply visit the official website and download the software again. Delete your current version and then install the new one.
There is also a possibility that your software reached the end of the trial period. When this happens, the full version needs to be purchased to continue to use it.