In this talk I will outline the calculation of effective material parameters of nonlinear metamaterials and discuss an effect of dynamic symmetry breaking in photo-metamaterials. The first part of the talk will cover the aspect of nonlinear metamaterials' homogenization taking into account spatial dispersion effects. It is demonstrated that nonlocality in nonlinear structures gives rise to a variety of new physical phenomena including generation of multiple harmonic beams with the same polarization and dependence of nonlinear susceptibilities on the direction of wave vector of the fundamental wave. The deviations from the local effective medium model in the vicinity of nonlinear inclusions resonances will be discussed. The second part of the talk is related to the phenomenon of dynamic inversion symmetry breaking in photo-metamaterials. Unit cell of such photo-metamaterial incorporates photodiode and light-emitting diode. It is demonstrated that additional optical interaction channel in such structures gives rise to the emergence of the nonzero second-order nonlinear suscepbility. Basing on the rigorous nonlocal homogenization approach we calculate effective nonlinear susceptibilities of photo-metamaterial and make suggestions on possible experimental observation of dynamic symmetry breaking.