Upload & extract the new version (4.3.0) to your website directory, you'll get a folder "valexa_4.3.0" with 2 subfolders (doc and script)

Create a folder named "update" in your script main folder (e.g. "/public_html/example.com/update")

Move "/valexa_4.3.0/script" content to the "/update" folder you just created

Copy "/update/public/update.php" to "/public" folder of your main script

Open your website on the browser with "/update.php" like (https://www.example.com/update.php)

Wait for script to finish the execution (updating), it may take a couple of minutes