Just like natural teeth, your veneers can stain if you aren't careful. Dark, highly acidic foods and drinks are the biggest culprits.
If you want to keep your smile bright white, avoid eating dark berries, tomato sauce, soy sauce, and dark chocolate while wearing them. Spices like turmeric and curry will also leave a yellow tint.
You can still enjoy coffee or tea, but it's best to drink them through a straw to minimize contact with the front of your veneers.