There are two answers:
Semi Permanent Eyeliner can last for many years, decades even, should you maintain your 12-18 monthly retouches (usually charged at half your initial cost)
Should you decide not to maintain your eyeliner by having these retouches, it will gradually fade from the skin. The pigment will become duller and will take a few years to COMPLETELY fade. An honest estimate will be between 3 and 7 years, it can be hard to determine for many reasons: For example if your practitioner has implanted the pigment too deep, or conversely too superficially into the skin. Or if you use Retin A creams and exfoliants. Also, darker colours like black will last longer than browns/ purples/ greens.
It is important to choose a practitioner who has trained to a high standard, has a portfolio of good work, and who you are comfortable with.
any questions please call or text 0785 313 4460
or visit http://www.precisionbeauty.co.uk/