How long do the bonds in a molecule hold under nominally stable conditions?
Water with its fluctuating hydrogen bond networks is a special case. If you feel for it, have a look at Water clusters: Untangling the mysteries of the liquid, one molecule at a time, but it doesn't answer your question ;-)

It is more interesting to have a look at paleochemical/geobiological findings.


A complex organic molecule, such as 2$\alpha$-methylhopane was isolated from 


  2700-million-year-old shales from the Pilbara Craton, Australia
  (Source)


Have look at the website of Roger Summons at MIT and his freely available publications, such as The Exceptional Preservation of Interesting and Informative Biomolecules.

In short, bonds can last a pretty long time!