Can I install Sketch on multiple computers?
When you purchase Sketch, your license entitles you to use Sketch on one computer only. If you have multiple Macs, or people using Sketch, you can either purchase a volume license at a discount, or add more seats to an existing license key.
If you’ve bought a new Mac and want to use Sketch, you’ll need to unregister Sketch from your old machine first. To do this, choose Sketch › Unregister Sketch… in the menu and confirm the alert that appears.