Educational versions (licenses) of AutoCAD releases older than 2014 SP1 stored a permanent information about using an educational version inside the saved DWG files. This identification was part of the license protection scheme -- licenses of the discounted or free educational and student versions of AutoCAD do not allow to use this software for commercial projects.
This limitation for using student and educational (school) versions for commercial work still applies. But you can now remove the visible portion of the information - the banner "CREATED IN AN EDUCATIONAL VERSION", which was displayed on plotted/printed drawings and when opening/inserting "edu" DWG files in standard commercial versions of AutoCAD.
This information can be now easily removed by opening the drawing in AutoCAD 2015 (or in LT 2015, or evt. also in TrueView 2015) and higher, and by just saving the respective DWG file (Ctrl+S).
Make sure that your AutoCAD usage is compliant with your licence terms.