I'm still confused by this. What is it in curry pastes that helps to preserve them? I looked at some info from the WHO and they recommend that foods shouldn't be kept for more than 10 days between the temps of 3 and 8 degrees unless:

a heat treatment of 90°C for 10 minutes or equivalent lethality at the slowest heating point in the food
a pH of 5.0 or less throughout the food and throughout all components of complex foods
a minimum salt level of 3.5% in the aqueous phase throughout the food and throughout all components of complex foods
a water activity (aw) of 0.97 or less throughout the food and throughout all components of complex foods
a combination of heat and preservative factors which can be shown consistently to prevent growth and toxin production by non-proteolytic C. botulinum

Is that why shop bought pastes often taste a little acidic? Do they add a little something something?

I purchased a jar of Simply Asia Thai Kitchen "red curry paste" for a red lentil and kambucha curry tonight. The little jar had a shrink wrap covering the lid, but it was not "vacuum sealed". Should it be vacuum sealed? Its made in Thailand and shipped to the US, and I though it might require a vacuum seal. What do you think?

I'm laughing, that you guys think 3 - 4 months is a long time. I just decided that it was time to replace mine. It's been about ten months, I think. Yes, I think changing those curry pastes once a year, whether they need it or not, is a good idea. (By the way, they don't last so long in the winter, when I use them a lot. But March through August I barely touch 'em.)

Glass jar isn't necessary - small plastic tupperware works fine, although you can't ever use it for anything else after that, as it will pick up the curry smell and it's nearly impossible to get rid of! But once transferred and kept airtight, it lasts a loooong time.

In the glass jar - i am counting on mine to last many months (a nice alternative to consider in the future is the Spice House Thai red curry powder for reconstitution - very acceptable substitute (better? yes.) alternative for the jarred version - trip to MKE or mail order is worthwhile - so good.)

Put it in a glass jar for storing. The metal can, once opened, can impart an unpleasant flavor to the paste. As Mr Vittles says, 3 to 4 months sounds about right. ;o)

As long as its in the refrigerator, then yes it should last for at least three months if not longer.