Hello Patmos,
Unless I’m mistaken at your specific question and not the other posts in this thread, I should say that there is no upgrade from Wavelab LE6 to Wavelab LE8. However you can upgrade from Wavelab LE6 to Wavelab Elements 8. Please use the following link to the online shop:
http://www.steinberg.net/en/shop/buy_product/product/wavelab-elements-8.html