We explore the hypothesis that adding conservation of matter to an artificial life system can increase its evolutionary activity, through experiments with the Stringmol artificial chemistry. Our first experiment examines the effect of varying the number of opcodes and finds a concentration which maximises the evolutionary activity of the system. The second experiment searches for the optimum relative concentrations of opcodes that maximises evolutionary activity: it finds increased evolutionary activity, a high diversity of opcode concentrations in each search run, and a different configuration of concentrations in separate search runs. The third experiment investigates the need for low concentrations of opcodes in high evolutionary activity, and finds that evolutionary activity decreases when more of these particular opcodes are provided. We conclude that conservation of matter provides an important evolutionary pressure that can lead to more diversity and more evolutionary activity, and is therefore a desirable property for experiments in evolving ALife systems.