If you are using your Maltego client license on a machine that is frequently being re-imaged, you should rather do an offline activation. Offline activation will create a license file which can be used to activate multiple times. (Provided it is only used on the machine that created it)

You can create a license file by choosing the "Activate without Internet" in the Product Selection window from within the Maltego client when it is run for the first time after installation and then follow the on screen instructions.

Read detailed activation process here: Initial Activation