This Integer32 (0 or 256..2147483647 kilobytes) is described as the number of kilobytes transferred before the SA is completely deleted, with 0 meaning this lifetime is withheld from proposals sent to the peer. An admin sets this on the shared policy to enforce volume-based full renegotiation consistently for every crypto map that references this policy. For example, an admin concerned about key exposure on high-traffic links would set a conservative kilobyte limit here so any tunnel using this policy rekeys well before massive data volumes accumulate under one key.