Activation code for wordpress themes (Anywhere) (South India)

Hi, I need a person that can develop for me an easy system to insert an activation code into a child theme for wordpress. I need to sell wordpress themes and I want to sell them with a license for one installation (for a small price) or for more ins ...
 
Apply here: https://bangalore.craigslist.co.in/web/d/activation-code-for-wordpress/6496728320.html