I 've read in several books explanations about lighting.
I want to know if the limit of height lights is resulting of opengl limit or if it’s possible to set more lights in a rendering ( for exemple with some new graphics cards utilities).



By specification, every OpenGL implementation has to support at least 8 light sources… there might be implementations that support more, but if you want your app to work properly on different platforms (graphics cards) you shouldn’t use more than 8.
You can use virtual light sources:
In your scene, determine which light sources don’t affect the scene lighting at your current viewpoint (you’ll have to implement some tolerance, say, if the distance of a light source to the objects in your view is bigger than 100 units, depending on the attenuation of the light sources).
These light sources you won’t need to light the scene from your current viewpoint, and they can be repositioned to represent other lights that do.
This way you can also cut down the number of light sources which might increase performance