When you upgrade from DU Meter 7 to DU Meter 8, DU Meter Taskbar Band will be closed to allow the program files to be replaced, and there is no Microsoft-approved way to re-enable it automatically afterwards. Therefore, it should be enabled manually:

On Windows 10

Right-click on any empty space on the Windows taskbar, select the top "Toolbars" submenu, and then select "DU Meter" from that submenu.

On Windows 11

Note that the taskbar band on Windows 11 is experimental in DU Meter since Microsoft removed this feature from Windows. To try it, select Taskbar Band from DU Meter pop-up menu.

If the taskbar band will no longer work properly for you in the experimental mode, we might suggest enabling DU Meter's mini-mode, also accessible from the main window's right-click menu. You can place this just above the taskbar if you like (although not on the taskbar as it will get lost behind it because of Windows controls) and you can toggle back and forth between the main window and the mini-mode with a double-click.