Please be very cautious when using an Educational version of AutoCAD 2014 SP1. There is a STILL an EDU watermark [plot stamp] but the warning is now suppressed in SP1. If you open the same EDU file with AutoCAD 2014, the EDU [plot stamp] warning will show up!
For more info on this topic, please review the following forum post:
To quickly see if your files are an EDU version, just review this blog post: