missing     /usr/lib64/gnome-settings-daemon-3.0/gtk-modules/pk-gtk-module.desktop
missing     /usr/lib64/gtk-2.0/modules/libpk-gtk-module.so
missing     /usr/lib64/gtk-3.0/modules/libpk-gtk-module.so
missing   c /etc/PackageKit/CommandNotFound.conf
missing     /etc/profile.d/PackageKit.sh
missing     /usr/libexec/pk-command-not-found
missing     /usr/libexec/pk-gstreamer-install

$ journalctl --since=-1month /usr/libexec/pk-offline-update
...
May 16 11:17:03 alan-laptop pk-offline-update[773]: package updating        ostree-2018.5-1.fc28.x86_64 (updates)
...
May 16 11:17:05 alan-laptop pk-offline-update[773]: package cleanup        ostree-2018.3-2.fc28.x86_64 (installed)

# dnf history PackageKit-command-not-found
ID     | Command line             | Date and time    | Action(s)      | Altered
-------------------------------------------------------------------------------
   338 | reinstall PackageKit-com | 2018-05-28 01:25 | Reinstall      |    3
   305 | system-upgrade upgrade   | 2018-05-02 14:30 | D, I, O, U     | 2798 EE
   280 | upgrade                  | 2018-05-01 22:24 | I, U           |   23 EE
   217 | upgrade                  | 2018-01-19 08:17 | I, O, U        |  224 EE
     1 |                          | 2016-11-15 21:27 | Install        | 1485 EE

TIME                            PID   UID   GID SIG COREFILE  EXE
Mon 2018-05-14 18:14:01 BST    4474     0     0  11 missing   /usr/libexec/packagekitd
Mon 2018-05-14 16:40:28 BST    1599     0     0  11 missing   /usr/libexec/packagekitd
Wed 2018-05-02 12:10:53 BST    2174     0     0  11 missing   /usr/libexec/packagekitd
Wed 2018-05-02 11:39:55 BST   27919     0     0  11 missing   /usr/libexec/packagekitd
Wed 2018-05-02 10:47:53 BST   25548     0     0   6 missing   /usr/libexec/packagekitd
Wed 2018-05-02 10:46:52 BST   21783     0     0   6 missing   /usr/libexec/packagekitd
Wed 2018-05-02 10:42:43 BST   18529     0     0  11 missing   /usr/libexec/packagekitd
Wed 2018-05-02 10:37:56 BST   12763     0     0   6 missing   /usr/libexec/packagekitd
Wed 2018-05-02 10:15:49 BST    1569     0     0   6 missing   /usr/libexec/packagekitd
Sat 2018-04-28 14:34:43 BST    1394     0     0  11 missing   /usr/libexec/packagekitd
Tue 2018-03-06 10:54:03 GMT    1498     0     0   6 missing   /usr/libexec/packagekitd
Wed 2018-02-28 10:40:55 GMT    1487     0     0  11 missing   /usr/libexec/packagekitd
Fri 2018-02-23 21:01:21 GMT    1557     0     0   6 missing   /usr/libexec/packagekitd
Thu 2017-11-16 10:05:46 GMT   10987     0     0  11 missing   /usr/libexec/packagekitd
Tue 2017-11-14 11:04:56 GMT    1631     0     0  11 missing   /usr/libexec/packagekitd
Mon 2017-10-16 16:56:48 BST    1557     0     0  11 missing   /usr/libexec/packagekitd
Thu 2017-09-28 16:31:19 BST    1513     0     0  11 missing   /usr/libexec/packagekitd