The general advice about unopened pouches was 3 to 5 yrs depending on how it he been stored. If it had been in a hot damp environment then it could be less. 6 months if opened and kept in a cool dry place. You can open it and see how it tastes and smells. You would notice it smelling off. It's still ok to consume, but as oxygen gets in the container it will start to degrade the micronutrients over time. It won't necessarily be "bad", just possibly reduced in nutrients which is important when using sole source.

The loss of Cambridge has been sad for us all. It's been part of my life since 1980 when it was brand new and I first used it and became a "counselor". We were called that back then too.

You might try checking eBay or other marketplaces. A lot of people bought huge stockpiles when it was announced they were closing and may be selling some off.