This is a very common concern and question that comes up in every consultation. How long does scalp micropigmentation really last!? I see claims out there that this will last 10 years or forever or only a year, etc. Most of these claims are incorrect, and a result of inexperience. If the artist is depositing the ink the correct depth, into the epidermis and properly tipping the dermis, the job should last 3-5 years. If the artist goes into the skin too deep, it will bleed out like a tattoo and last much longer. But if the spacing, density, and depth are done correctly, it should age nicely, with grace as it lightens up over the years.
Now remember everybody's skin is different, some people may need it sooner, some may be fine going much longer and don't mind the natural look as it lightens up. But the average client will come in for a touch up in that 3-5 year range. I had a touch up myself after about 4 years, and now it's been another 3-4 years since my last touch up.
It is important to note a few things when it comes to SMP touch ups. You must wait until the pigment has lightened up considerably if you really want to get a nice looking, clean touch up done. If you still have lots of dark pigment, it will be pointless to add more ink, and probably even harmful as you do not want the pigment to bleed and blend together, like a tattoo on your head.
If there is lots of space and lightened areas, we have much more room to add pigment and create a nice fresh layer on top of everything, this usually looks amazing when done correctly, and it usually only takes 1 session (maybe 2 if you've lost a lot of ink, or a lot of hair in between treatments). Since the SMP touch up is usually only 1 session, it should only cost about a third of your original treatment cost. So maintenance is fairly easy and inexpensive considering this really should only be needed once every 3-5 years.