i had a one year education license installed on my old laptop, now I got my new laptop, and tried to use the same license code to authorize it on my new laptop, and I couldn't as its a single use license.
any help.
I would recommend you to contact Esri Technical Support before proceeding with these steps.
Firstly, you must deauthorize the license installed on your old laptop. Then you can do authorize process on your new laptop.
How To: Perform online deauthorization of licenses for ArcGIS for Desktop and ArcGIS Engine
Regards,