QLM can track illegal computers that connect to the License Server and logs information about these computers in the database. An illegal computer is defined as a computer that has a valid license key but whose license key is (a) not in the database or (b) in the database but registered for another computer. This situation can occur if a user with a valid license key requests that his license be released from computer A claiming to have uninstalled your program from computer A. If the user subsequently attempts to connect to the License Server via computer A, QLM detects this computer as an illegal computer and logs it in the database.
You can access the list of detected illegal computers from the QLM Management Console / Manage Keys / Illegal Computers. QLM does not prevent all illegal computer from running your application. Once an illegal computer is detected, it is up to you to decide the course of action to take by contacting the customer and enquiring about the situation.
You can access the list of detected activation attempts from the QLM Management Console / Manage Keys / Activation Attempts. A failed activation is typically due to multiple attempts to activate the same license key on different computers. Though failed activation attempts may indicate an intention to illegally activate a license on a particular computer, they can also be regarded as the sign of a user who needs additional licenses for your software.