Under Windows 7 LogMeTT icon in notification area will become hidden in about 45 seconds after the first installation. This behavior cannot be changed programmatically; see the explanation from Microsoft pasted below. To make LogMeTT icon always visible customize Windows Notification area and set LogMeTT icon behaviors to "Show icon and notifications".
"There is no way for applications to programmatically always show themselves top level on the system tray either on first install or at any time during runtime. This is one of several changes we’ve made in Windows 7 in an effort to produce a cleaner, quieter desktop that is in the user’s control to customize the top level with their favorite applications and icons.
We keep the user in control of the notification area by not allowing programmatic promotion (other than temporarily or to show a notification). Assuming the machine is sufficiently quiet, when you first add your icon with Shell_NotifyIcon(NIM_ADD, ...) it will be shown on the taskbar for 45 seconds, then move into the overflow
thereafter. If the user promotes an icon, it will always live on the taskbar. If the user demotes it, the icon will never be seen on the taskbar. Any promotion needs to be user initiated. We’ve made this much easier in Windows 7 via drag/drop & through the Notification Area Icons control panel, and what we’ve seen in usability studies and based on beta feedback, is that users have no difficulties discovering how to customize notification behavior and will promote the icons they want quick access to.
Source: Microsoft TechNet