Can I Change My License Name

Hi guys 1st Question Comes Here Why Do You Need To Change Your License Name
I Had A Client And I Have Done Alot OF Work For Him And He Had A Website Created And Now Its Offline And He Also Had Gsa Ranker And Gave That to me , Free No No Actually i told i have done work for him so he given me the software as for the work i have done for him and So Guys Can I Change My Username of that license and change it to mine