Like how long can the juice stay in the animals sacks before it starts to deteriorate? Does it start to smell bad?

If essence is held in the sac and frozen it will remain stable. Keep out at room temperature over time the sac tissue will begin to break down then the essence can begin to change in odor. It will become more difficult to extract the essence once the tissue breaks down. Things will get dicey.

Tap it put it in glass bottles with a metal lid then freeze it that’s more for evaporation then it going bad, if you leave it the sacks unfrozen then it might get contaminated when the sacks breakdown.

Thank you. How long is it good in the animal in this cooler weather?

In general id say no skunk essence doesn't go bad over time. The main risk is it fades pretty fast if not fixed or stored correctly.