Used to be Stability and Cycle were all there were in a long shelf-life product. These contain heterotrophic bacteria that multiplies equally well in aerobic and anaerobic conditions. Those bacteria multiply orders of magnitude faster than the autotrophs (nitrosomonas and nitrospira) which require oxygen but really perform the nitrification.
Cycle, Stability and their ilk keep ammonia from getting dangerously high during the time the autotrophs are growing, which is why they have been recommended and work, after a fashion.
Live autotrophs have a relatively short shelf-life, one reason the retail stores are loath to carry them. Safestart was derived from Biospira invented by Dr Tim Hovanec. This formula was sold to Tetra and became Safestart. Dr Tim now markets his own line of AQ chemicals and bacteria. His nitrifying bacteria (One-and-Only) is shipped from his facilities cold in an insulated container.