Set the Plays ("Play Count" before iTunes v9.2) of the selected tracks to a user-entered number (they will all be set to the same number). If this number is 0 then the Last Played date of each track will be erased. (iTunes has the ability to "Reset Plays" to 0 from a track's contextual menu.)
Also see Add or Subtract Play Count.
Apple Music users should beware of a potential bug.
Perhaps Also of Interest...
downloaded 3m 0s ago
Select iPod tracks in iTunes and add them to iTunes
downloaded 3m 31s ago
Assists with finding truncated iTunes Match tracks
downloaded 7m 1s ago
Drag-and-drop to convert audio files with iTunes
downloaded 14m 46s ago
Write size of track's artwork to chosen tag or copy tracks with artwork of certain size to playlist
downloaded 28m 50s ago
Title Cap various track tags, featuring editable exceptions lists
downloaded 41m 11s ago
Batch-change the Album Rating for the albums of selected tracks