The license can be revoke, after that the key is able to activate a different machine.
To revoke the license, please go to Marmalade Hub interface.
In the upper right corner it should be displaying the license information.
Click on it will bring up another dialog with "Revoke" button, click on the button then it will be revoked.
After revoke, the key is able to activate a different machine.
If you want to move back, just revoke again and then re-activate.
Please make sure you have Internet connection while revoking, otherwise the revoke process will fail.
In case your dev machine somehow went down(hope that won't happen) and you might not have a chance to revoke it while it's still alive, please contact us for help.