TheGamesDb.net

I'd like an API so I can work on a personal project to create an automatic game recommendation based on my previous games played and scores.

Hello.

You've been granted an API key which you can access through this page.
Please check the Announcements forum on a regular basis to ensure compliance with any changes or updates.
Documentation is available here.

Good luck!

If my request which are 6k finished, in that case, what will happen?

Private key has been made for devs to mirror the DB. It will never be refreshed.
Public key has monthly limit per IP. You should use it in your app.