I've read in some other forums where persons claim to have been on maintenance protocol with Reta and used 10/12 mg vials for 8-12 weeks with no adverse effects. Claimed they still felt the benefits. I get this isn't much help. So many variables, sterility, storage, bac water used and age. If the vial has no floaters, remains clear it may be fine to continue to use. But I would suggest you become the experiment at that point. Personally, if the purity being above 99% and volume was on point for the vial in question. I'd just ensure refrigeration, hygiene, disposition of the vial (no cloudy or discoloration, particles) I'd continue to use it and just really focus on how I felt for a period of time after injection.