Apple has recently released the new public beta software program that is macOS Mojave 10.14.4. If you’re already using macOS public beta program, then go to your Mac’s System Preferences and update it. If you’re a new user, then create a backup before installing the public beta program.
How to register for macOS Mojave 10.14.4 public beta 1 with your account
If you’ve previously registered for a public beta program then there is no need to register again for macOS Mojave 10.14.4, just use the same registered Apple ID on your Mac and install public beta for free. If you’ve never registered for the public beta program before then to get it on your Mac, first register your account for the program.
Here are steps to register your account for public beta macOS 10.14.4