The program states that the software can be used on two devices simultaneously. But I upgraded my computer and when I download vs 16, and then tried to register, it says that the serial number is already registered and to contact Magix support. I went through this before when I bought vs 15 but can't remember how to solve this.
You can deactivate all old installations in your user account at https://www.magix.com/int/support/my-service-center/ Then you will have free slots for new installations. You can also change your e-mail address there.