I cant find it and i've gone through all the folders.
When you launch Unity, it asks you to choose manual or internet activation. Choose the manual activation and then there are two buttons. One says "Save License Request" which will allow you to save the files you need to choose on https://store.unity3d.com/manual. After saving it, you just find the file that you downloaded from the Unity website and select it with the "Read License" button.