Question

How long can a nebula live?

Answer 1

It depends on the size of the star it creates.

Explanation:

For a star the size of the sun, it takes ~10 million years for the nebula to collapse.
For bigger stars, it takes a shorter amount of time; as short as 100,000 years.
For smaller stars, it can take far more than 10 million years.
(http://passporttoknowledge.com/lfs/QA/Lifespan_of_a_Nebula.txt)