True colloidal silver has an indefinite shelf life to the best of our knowledge. Its simply nanoscopic sized particles of silver floating in water - there's nothing to decompose or go bad.
Ionic silver is what you'll find commercially. If its water clear, its ionic, NOT colloidal regardless what the labels say and most of it is 10PPM which is a joke. True colloidal silver is kind of apple juice color. You'd need to ingest at least 8oz, if not more of 10PPM commercial to do anything within the body but I would not recommend ingesting ionic silver. Its not good inside the body.
You'd go bankrupt trying to heal yourself taking commercial stuff where for very little "pain" you can be making your own on your kitchen table or kitchen counter at 20PPM for all of about $1 per GALLON (where most of that cost is what the distilled water costs - silver amounts to 10 cents or less per gallon at current silver prices). Yeah, I'm serious. And the total outlay in cost of supplies won't be much more than those health food store vendors charge for a single 2oz bottle of their 10PPM ionic silver, excluding the cost of the silver which as of today is about $16/ozt - a 1ozt silver bullion bar - a single one will last you a lifetime - will make over 400 gallons of 20PPM - seriously.
Stick around, read the articles, learn all you can and I think you'll see that making it yourself is the ONLY way to get quality colloidal silver you actually trust to be colloidal silver and trust to ingest, knowing it won't harm you and will only help. Its also simple to make though you do have to follow through and follow the procedures. This is real chemistry and you're making something you're going to drink so you need to pay attention and do it right but most guys here or who have been members in the past nailed it on their first try, myself included.