The License Splashscreen is shown up for a few seconds whenever you start LEX - The LDAP Explorer without an activated
You can get rid of this by choosing the option Activate existing license - what you need here is your LEX license file.
You can also activate your license later in the application by choosing the option Help - Activate existing
In the dialog Please load the LEX License file, you can choose and load your LEX license file. Then your license is activated and you can use LEX without any limitations: