This work proposesan adaptive control methodology for a class of time-varying uncertain systems. The goal of this work is to address problems in which the model is known, but the parameters involved are either unknown, time-varying, or the system is being affected by disturbances. The proposed methodology relies on Lyapunov control concepts and the bound of the time-varying elements (only the boundedness feature is known) to extend traditional adaptive control techniques restricted to linear constant parameterization. In order to show the efficiency of this methodology, we present a comparison simulation and an implementation for speed tracking in a Brush-Less Direct Current (BLDC) motor under parametric uncertainty.