Hi,
Okay, thanks for the clarification. You can edit the file /etc/xdg/autostart/gnome-software-service.desktop and set the NoDisplay option from true to false, causing Gnome Software to appear in the “Startup applications” list (you may need to log out, and log in again), as it is hidden by default. You can disable it there, and may need to reboot/restart gdm for the setting to take effect.
Please let me know if this works for you.