Living molecules are evidently interested in their existence. In inorganic forms there is no such thing.
Generally, living molecules -- in their special way -- are quite robust forms.
The type of inorganic transience (as in peroxy compounds) and inorganic transformational instability (many energetically favorable transitions in organic chemistry) is certainly totally different from the so-called organismic instability or transiency. Quantum mechanically and as to quantum situations this can be represented in a useful form.
As an essential feature of the living substance (not so conspicuous as the ability to regenerate, self-reproduction, and others) we have the buffer effect against noxious environmental influences (molecular impacts, radiations, etc., which disturb or destroy, or may be bond-breaking), and to this ability to buffer evidently belongs a minimal size. It is clear that in order to achieve effective buffering, the living molecule must be sufficiently large, whereby we must think of the buffer effect as an "elastic" cushioning and setting off of noxious influences, as well as in the form of a triggered repair of a damaged part from the intact neighborhood ( Essentially it is an induced triggered restitution, a bit comparable to the chemical "conductive principle". In terms of process one may think of a [molecular] self-amputation, followed by a complementing synthesis under cooperation with RNA as prosthetic group of the "whole". To the peptidic self-amputation products one may ascribe the function of RNA-activating or anti-blockade substances (compare "wound hormones", and others)). In both cases (elastic cushioning, triggered repair) not too small a molecule is favorable. Between sensitivity, buffering, self-feeling, self-sensation, there are qualitative as well as genetic [i.e. qua generation] relationships.