We have used 2/5 seats on our AutoCAD 2009 product. However, when going to register for the third seat, the screen displays that "The serial number you entered is not valid. Try again. (1)" This is the same serial number we have used for the first two seats, but now it will not work.
If your product was upgraded or was on Subscription that has expired, you will get this message. You might have to contact Autodesk or your Reseller directly about this. Do not share your serial number here.
Please call Autodesk Product Registration and Authorization: