Putty is open source software that is available with source code and is developed. Bitvise ssh client, which has similar functionality to putty, is available free of charge for use in any environment. Looking for putty, the software?
Putty is an ssh and telnet client, developed originally by simon tatham for the windows platform. The putty project or its authors have never owned this domain, registered. Almost no one purchases a license to use it.