While Snagit will never automatically delete files from your Library, other applications can do so.
Most commonly, we see this with Advanced SystemCare and CCleaner. If these cleanup tools are run with Snagit selected from the list of applications, the captures (.SNAG) that are automatically saved to these locations may be deleted from the hard drive:
C:\Documents and Settings\YOURUSERNAME\Local Settings\Application Data\TechSmith\SnagIt\DataStore
While Advanced SystemCare and CCleaner are known to do this, other disk cleanup tools can do this as well.
Snagit cannot perform any recovery of these deleted files. If a backup of this folder location has been made prior to these files being deleted, it's recommended that they be restored from the backup files. It may also be possible to recover the files through 3rd party tools.