Answer:

A New Extended Key is a code that may be used to activate Foxhound Version 3 as an Extended Edition copy after

• installing a fresh copy of Version 3 (without upgrading from an existing copy of Version 1 or 2), or

• upgrading an existing copy of the Version 3 Rental Edition.

You can purchase a New Extended Key here:

See also...
What are the differences among the different editions of Foxhound: Rental, Basic and Extended?
What are the differences among all the activation keys?