The Heimdal PRO license can be activated only on a single machine. Once you activated the license key on a machine it will not work on another one. So make sure to activate the license on the machine you want Heimdal to protect it.
The same applies if you change your Windows operating system or you buy a new computer.
*the above doesn't apply for the Family Edition (See also: What is the Heimdal Family Edition?)
What do I do in this case?
You need to contact our support team and they will provide you a new license key and cancel the old one. To do this, send an email at firstname.lastname@example.org.
Also, if you wish to have more than one license, please see our Family Edition option.
If you are a company, please contact us at email@example.com for more information on Heimdal CORP.