When you open a DWG file or just start your AutoCAD, you get a warning message (dialog):
The drawing file being opened was not created by a product from an Autodesk Education Suite.
If you save this drawing, it will always be plotted with the following plot stamp: PRODUCED BY AN AUTODESK EDUCATIONAL PRODUCT. It is recommended the you save this drawing with a different name.
AutoCAD always warns you if you are opening a DWG file created/saved by an EDU version into a commercial version, or - as in this case - vice-versa: you are opening a standard DWG file in an educational version of AutoCAD (and there is a risk you may "pollute" it with the EDU stamp).
If you see this message right after start, without opening any particular DWG file, you have probably selected a wrong (non-EDU, commercial) template file (DWT) for your EDU version of AutoCAD. Just choose a different .DWT file (see Options > Files) or re-save your existing DWT drawing template file (e.g. ACADISO.DWT) - it will receive the neccessary "EDU stamp". You can save the updated template to the original folder with A > Save as > Drawing template.