If you need to transfer the license back and forth between two computers (i.e. PC and Laptop, or Work and Home), you can manually release the license.
On v2018 or newer:
Launch your active copy of Alibre, click the Utilities tab and then click Release License.
On v2017.1.2 or older:
Launch your active copy of Alibre, and on the Home window click Tools>Release License.
Then, you can activate the software with your key on your second computer and vice versa.
Note: It is ideal to save the key in a Notepad file on your computer(s), so you will have easy access to copy and paste the key to activate the software.