A single user licence allows you install DesignBuilder onto a maximum of 2 computers for personal use, for example one on a desktop and one on a laptop. If you need to use the software on a third computer then you must first deactivate one of the other 2 computers.
When you purchase a DesignBuilder single user license, you will receive an 8-digit activation code. To use this enter it in the License dialog accessed from the Help menu within DesignBuilder and press the Activate button. This will cause DesignBuilder to automatically download licences for all modules associated with the activation code and activate them. You will then be able to use the software and run functionality associated with each activated license.