In this talk, we present new subgradient methods for solving nonsmooth convex optimization problems. These methods are the first ones, for which the whole sequence of test points is endowed with the worst-case performance guarantees. The methods are derived from a relaxed estimating sequences condition, and ensure reconstruction of an approximate primal-dual optimal solution. Our methods are applicable as efficient real-time stabilization tools for potential systems with infinite horizon. As an example, we consider a model of privacy-respecting taxation, where the center has no information on the utility functions of the agents. Nevertheless, by a proper taxation policy, the agents can be forced to apply in average the socially optimal strategies. Preliminary numerical experiments confirm a high efficiency of the new methods.