We develop a nonlocal dielectric-response theory to describe the temperature dependence of exciton lifetime in metal-semiconductor heterostructures. Coupling between excitons and surface plasmons results in a strongly nonmonotonous behavior of exciton decay rate versus temperature, affected by surface plasmons on both sides of themetal layer. Unlike the photons, surface plasmons are not able to escape the sample; hence, the additional decay channel for excitons appears solely due to the plasmon scattering in metal and metal-dielectric interfaces. Tuning the plasmon frequency, one can control the exciton lifetime and under certain conditions emission efficiency.