The location and number of backups retained are set using the PRSMon Tools->Options... menu command.
If the Backups retained option is set to zero (using the Tools->Options... menu command) then backups will be disabled.
Backup files created by the PRSMon Compact and Backup Database command have _<yyyymmdd>-<hhmmss> appended to the file name, where yyyy is the 4 digit year number and mm, dd, hh, mm, ss are two digit month, day, hour, minute and second numbers respectively. For example the backup file prs_data_20010420-134000.mdb was created at twenty to two on the 20th of April 2001.