With a synthetic, faux mink, or silk lash extension attached to your natural lash. 

It doesn't if applied properly 

Lash extension can  last up to

4 - 6 weeks with proper care. Fill are best every 2 - 3 weeks . Fills  are when you add  more lash extension to the gaps of the lashes that have fallen out.

A lift is essentially what your lash would be doing with a really good lash curler, giving your lash a nice upward curl.  Lash lift can last up to 6 - 8 weeks.