Nano brows, also known as nano needling or nano blading, is a type of semi-permanent makeup that uses tiny needle tips to deposit pigment into the skin. The longevity of the results can vary depending on several factors, including:

1. Skin Type: Oily skin tends to fade faster than dry skin. This is because the natural oils in your skin can cause the pigment to blur or fade.

2. Lifestyle: Sun exposure, frequent swimming, and excessive sweating can cause the pigment to fade faster.

3. Aftercare: Proper aftercare is crucial to prolong the results. This includes avoiding sun exposure, not picking at the brows, and keeping the area clean.

4. Skincare Routine: Certain skincare products, particularly those containing retinoids or acids, can cause the pigment to fade faster.

On average, nano brows can last anywhere between 1-3 years. However, touch-ups are usually recommended every 12-18 months to maintain the shape and saturation of pigment. It's important to note that everyone's skin responds differently to the pigment, so these timelines can vary.

As a skincare expert, I would advise you to always consult with a professional before making any decisions related to your skin. They can provide you with personalized advice based on your skin type and lifestyle.