Remember that both username and passwords are case sensitive.
Then, Sign In to the Xojo IDE on the new machine to activate your license there. If you have free activations but see the machine you are trying to activate on now already listed, OR if you don't have any free activations, click the 'x' next to a machine to deactivate your license from that machine. If this doesn't download your license to the Xojo IDE, go to your license key page at the Xojo website and verify you haven't used all your activations already. Your keys will be downloaded automatically. Then sign in using the same username and password you use at and on the forums. Launch Xojo, choose 'License Keys' from the drop-down menu (Windows & Linux: Help > License Keys, Mac: Xojo > License Keys) then click 'Update'.