1. “Check for updates” cross-references the server, querying your Serial number for any changes that may have been made since you last activated. This is handy for updating your license to include new add-ons once purchased and added to your existing license via the Unity Store.
  2. “Activate a new license” does what it says on the tin. This enables you to activate a new Serial number on the machine you’re using.
  3. The “Return license” feature enables you to return the license on the machine in question, in return for a new activation that can be used on another machine. Once clicked the Editor will close and you will be able to activate your Serial number elsewhere. For more information on how many machines a single license enables use on, please see our EULA.
  4. “Manual activation” enables you to activate your copy of Unity offline. This is covered in more depth above.