Notepad++ isn't showing "Update Notepad++" menu item

Solution 1:

There are four different versions and you need the Installer version.

Installer: Take this one if you have no idea which one you should take.
zip package: Don't want to use installer? Check this one (zip format).
7z package: Don't want to use installer? 7z format.
minimalist package: No theme, no plugin, no updater

The update helper GPU.exe is only bundled with the Installer version.
Even the .zip and .7z version don't come with the auto update functionality.

The update helper is located under ...\notepad++\updater\GUP.exe

Solution 2:

There could have been a problem during installation. Try uninstalling and reinstalling Notepad++.