There are a few different ways to make suction cups stick permanently. One way is to use a strong adhesive, such as super glue or epoxy. Another way is to use a suction cup with a built-in adhesive disk, such as those made by 3M. Finally, you can purchase special adhesives designed specifically for use with suction cups. Whichever method you choose, be sure to follow the manufacturer's instructions carefully to ensure the best results.