How long will pickled mushrooms keep?

this is aquote from a shrooms site, regarding to truffles but i guess might be quite accurate for other shroom types:

What is the shelflife of normal packed truffles and vacuum packed truffles?

Normally packed mushrooms can be kept for 1 month in the fridge. Unopened, the shelf life of a vacuum pack is 2 - 3 months, BUT the longer it stays in vacuum the shorter the shelflife is after opening.

i.e. if you open a vacuum bag immediately after arrival, (fresh as possible) the shelflife of the opened bag would be 1 month. If you open a vacuum bag after 2 months, the shelflife of the open bag would be only 1 week. Due to the vacuum certain reactions take place which shorten the shelflife after oxidation.