Posterity requires that you have a STI panel within 6 weeks of producing a sample if you’re planning on freezing it.If you have completed an STI panel with Posterity or another provider within that 6-week period, you can purchase the yearly storage plan on its own. If, by the time you produce the sample, it will be more than 6 weeks since your STI panel, you should purchase yearly storage + STI test kit.