  We demonstrate that the conditions of spaser generation and the full loss
compensation in a resonant plasmonic-gain medium (metamaterial) are identical.
Consequently, attempting the full compensation or overcompensation of losses by
gain will lead to instability and a transition to a spaser state. This will
limit (clamp) the inversion and lead to the limitation on the maximum loss
compensation achievable. The criterion of the loss overcompensation, leading to
the instability and spasing, is given in a analytical and universal
(independent from system's geometry) form.
