Will Juvederm prevent lip wrinkles if I start getting it at age 19? Will my face be dependent on it?

An injectable filler does not prevent future wrinkles from forming. It will just work to fill in the wrinkles that are present. Botox, however, can be preventative. For example, if an individual frequently frowns, the Botox can decrease the frowning, thus decreasing the lines that will appear in the future.
Juvederm is a great filler for lip augmentation. When the injections are performed properly, it yields a great looking and natural result. The Juvederm will not leave you dependent. I hope this helps, and I wish you the best of luck.

Juvederm won't "prevent" wrinkles per say, but can enhance volume if one has volume loss in a given area.  Juvederm in the lips will provide a more fuller lip, and I would recommend treatment with a board-certified dermatologist or plastic surgeon for treatment.