You can purchase the latest version of CosterGraphics Outline System Pro in the Unity Asset Store. When you have purchased it, you will be able to download and import it into your projects directly in the Unity Editor via the Unity Package Manager.
The license for CosterGraphics Outline System Pro is the Unity Asset Store Commercial License. Check the Asset Store for the exact specifications.
The Outline System costs €118.51 (+VAT where applicable). It includes free upgrades to all future 1.x versions of the package.

CosterGraphics OutlineSystem Pro
CosterGraphics Outline System Pro for the Unity Universal Render Pipeline
A highly versatile and easy to modify system for rendering professional Screen-Space Edge-Detection based Silhouette & Contour Outlines and Overlays around and onto any 3D model in the Unity game engine.
Fully utilizes the Unity Render Graph API and Shader Graph shaders, to efficiently render sharp and technical, or highly stylized NPR outlines, onto selected game objects only or onto the entire scene.
Also contains many other full-screen edge detection and mask overlay effects for full-screen NPR styles and sci-fi effects.
Built for the Universal Render Pipeline.