Where in macOS High Sierra is the "Updates Installed in the Last 30 Days" information from the App Store stored? In macOS Sierra this information was stored in: 

~/Library/Application Support/App Store/updatejournal.plist


But in macOS High Sierra this file only contains the 3rd Party Apps from the App Store. The Update Information from Apple Updates is apparently stored somewhere else

Is there a second file somewhere else, or where is this information now stored?
It’s in a different location now:

/private/var/db/softwareupdate/journal.plist

Don't forget to reboot.