Funny you should ask as I just started my own B&W film processing yesterday with that developer (I'm new to this home darkroom stuff). I think the most life you can get out of the stock solution is six months. That's all I'm banking on. That's for one liter in a sealed container. I follow the advice of a contributor to Black and White World whereby I hold my breath for long time and then exhale gently into the bottle to displace as much oxygen with carbon dioxide. We'll see how well it works. It's certainly cheaper than buying O2 displacement spray cans.(posted 8390 days ago)And I quoth from the notes on the inside of the box: ID-11 stock solution developer will keep: 6 months in full airtight bottles, 4 months in deep tank with a floating lid, 1 month in half-full tightly capped bottles, 24 hours 1+1 or 1+3.
As for storage, I've found that the nice, 1L clear Rubbermaid bottles with the white, snap-cap top do quite a fine job. Since I store my developer in a dark cabinet, I'm not so worried about it oxidizing from exposure to light.