i have tested my alone theme on localhost and is now registered on that domain.but i want to use for another website
You can try some webhost for free.
for solving purchase code or item license issue will need to get support from the item author. They (author) are the right team to help. you can contact item author through item comments page or author profile page or best option is through item support page.
How to contact an author to get support or for any technical query: