We consider DNA circuits in which the circuit function alters according to conditions, unlike typical DNA circuits, which have fixed functions embedded. In a typical design, DNA circuits cannot respond normally in a time-responsive manner to repeatedly applied inputs. However, it is required that DNA circuits have a renewable mechanism to “memorize” input history and to alter circuit functions plastically and adaptively by “learning.” Here, we provide some typical design strategies for a renewable mechanism intended for DNA circuits, and a classical conditioning circuit is introduced as an example of DNA circuit design with memory and learning capabilities.