Best Blackhat Forum

I want generatepress theme (purchased) with api key . :)

You don't need API (license) key, it's only used for auto-updating:
generatepress.com/forums/topic/more-functions-with-or-without-license-key/

---

Unless you want the Premium pack, which is here (do a search):
bestblackhatforum.com/Thread-PURCHASED-GeneratePress-Premium-SUPER-FAST-THEME-LATEST-ALWAYS