Mainstream standard LSTM architecture that is currently used in Tensorflow library does not use the original architecture. In fact, there are many different architectures of LSTM. One of the more widely used architectures of LSTM is Coupled Input and Forget Gate (CIFG). It is known more as Gated Recurrent Units (GRU). This chapter will introduce the existing architectures of LSTM. Further it will present memristive LSTM architecture implementation in analog hardware. The implementation realizes the standard version of LSTM architecture. Other architecture variations can be easily constructed by rearranging, adding, and deleting the existing analog circuit parts; and adding extra crossbar rows.