How long does bleaching your teeth last?

Depends: If one tends to have habits that stain teeth such as smoking, coffee/tea, red wine, etc. And doesn't brush well then the staining will return sooner than someone who does not have habits that stain. I like any otc whitening toothpaste with a power toothbrush like the sonicaire to maintain the white. A little baking soda/peroxide slurry on the brush helps also.

3 months to 1 year: In most cases, the bleaching results will last for a minimum of 3 months and can last up to a year or more.