Credits is a special feature in SketchUp where users can associate their models with themselves. If a model is uploaded to 3D Warehouse with the credit claimed, then whoever download the model will able to see who has contributed to it. A google account is needed to claim credits.
How to claim credits Edit
1. In the bottom left-hand corner, click the G button which indicate google account.
2. Sign in if you are prompted.
3. After signing in, click Window > Model info > Credits. This will open the credits window.
4. Click Model authors, and then click Claim credit.