In this paper, new fully floating memristor emulator circuit that consumes ultra-low energy is presented. This proposed circuit is simple because of the fact that it doesn't contain any multiplication or various block circuits to obtain nonlinear characteristics of memristor. Transistors are operated in subthreshold region to obtain the non-linear behavior. Floating Current Source (FCS) is used in memristor emulator design to decrease the energy consumption of emulator. Associative learning is a type of the learning mechanisms and designed memristor are used in classical associative learning circuit successfully. All results are compatible with both memristor characteristics and learning mechanisms of circuit.