This product https://cabaech.pe/product/audifonos-bluetooth-haylou-w1-t60/ is the variable product. So, you need to choose the variations before adding a product to the cart, that’s why once you click “Buy now” button page scrolled up to the variations area. The simple product could be added to the cart directly from the sticky panel. That is the difference.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.