Diskeeper Lite is a great freebie but the nag screen is extremely intrusive. So intrusive that it goaded subscriber "Koolance" to find a way of removing it. Here's the way he did it:
"1. First make sure you have set file extensions to be displayed in Windows Explorer. To do this open Explorer and go to Folder Options / View tab and uncheck "Hide extensions for known file types".
2. Open Notepad and without writing anything select File / Save as and then name the file "ShowHtml.exe". In other words create a blank file of that name.
3. Open the directory you installed Diskeeper Lite in. Normally this is C:\Program Files\Executive Software\DiskeeperLite. Copy and Paste the file you just created into this folder. Select YES when ask if you want to replace the existing file.
That's it. No more nag screen! The buttons in Diskeeper Lite that bring up the "Nag Screen" will now do nothing.
If you want to, go back to Folder Options-->View tab and un-check "Hide extensions for known file types".
Another useful trick with Diskeeper Lite is to add automatic scheduling. This useful feature is available in the full version but not the Lite. I described how you could set up automatic scheduling here.