Yeast harvesting question

I recently harvested the yeast from my blow-off container. The stuff in the bottom of the container appeared to be just yeast and water, so I poured off the water and dumped the yeast slurry into a sterilized mason jar.

Can anybody tell me how long that yeast will remain viable in the refrigerator? I'd like to use it in a future batch, but not necessarily in my next batch. Will it last a couple of months, until I want to brew another lager?

I don't know that I would use yeast found in my blow off container. The blowoff container is usually open and wild stuff can drop in there.
Take the yeast from inside your fermentor after you rack off the beer. This stuff is good for months in the fridge.