Many people, like Kendall Jenner, choose to go for an inner lip tattoo on a whim (via Allure). For those who aren't in love with the ink they've chosen after the tattoo is complete, there's some good news. The average inner lip tattoo is expected to start fading after one to five years, making it more of a semipermanent decision, according to Bustle. Board-certified and New York-based dermatologist Dr. Hadley King says that this is because oral skin cells turnover much faster than external skin cells. While the fading will be significant, there is a chance that, even once it's almost fully faded, you will still have a permanent mark on the inside of your lip.
If you want your inner lip tattoo to last, it's important to find an artist who has some experience with the placement. A more experienced artist will be sure to get the ink deeper in your skin, which will make it last much longer. If you'd prefer that the ink fade faster, make sure your artist doesn't go too deep (via Bustle).
As with any tattoo, you'll probably want to put a significant amount of thought into your inner lip tattoo. If you don't, however, it will be pretty easy to hide in the event that you don't like the final product.