In this article we discuss the science enabled by heavy quarkonium production in electro-and photo-production on a proton, its possible relation to the determination of the trace anomaly contribution to the proton mass, and the search of LHCb charm pentaquark. We describe the elastic threshold J/ψ production experiments carried out or planned at Jefferson Lab. We also discuss a possible elastic threshold ϒ electroproduction measurement on a proton at a future electron ion collider (EIC).