Please check if the installed version of MAXQDA matches with the version of your license. For example, you need to enter a MAXQDA 12 licenses to unlock an MAXQDA 12 installation. If the license is for MAXQDA 11, the license cannot be used to unlock an installation of MAXQDA 12.
Please also check your serial number for typing errors. If you still receive this message, please get in contact with our support team. The technical support can be contacted through this form: http://www.maxqda.com/support/onlinesupport