<p>Logic operations at the molecular level are anticipated to play key role in data processing and storage in the future. However, most of these chemical systems rely on foreign chemical inputs. In contrast, opto-chemical logic devices are simpler to implement due to the ease of optical changes compared to pure chemical ones. In this work, a semicarbazone Schiff base derivative (E)-2-(4-(diethylamino)-2-hydroxybenzylidene)hydrazine-1-carboxamide (DHHC) has been developed as a photo-switch, enabling the design of multifunctional logic systems, most importantly, independent of foreign chemical inputs. The mechanism operates based on the concentration-driven optical properties of DHHC, where native inputs, such as methanol and DHHC itself, influence its optical behaviour by altering system concentrations. As confirmed by 2D contour plots, the distinct emission profiles of lower and higher concentrations of DHHC are strictly governed by their respective excitations. These self-sufficient optical properties of DHHC were leveraged to design several interconvertible simple and complex logic gates, including INHIBIT and IMPLICATION gates. Additionally, the photo-switching ability of DHHC was utilized to generate a memory device with a feedback loop mechanism, with methanol and DHHC acting as “reset” and “set” conditions, respectively, demonstrating an infinitely recyclable “Erase-Read-Write-Read” memory function. The fluorescence responses of DHHC were also employed to develop two potentially highly secured molecular keypad pattern locks, functioning with purely opto-chemical passwords. This work showcases the hidden potential of a light-responsive Schiff base as a multifunctional, reconfigurable molecular logic device, advancing the development of molecular data processing and data security elements.</p>