How long should you keep powder foundation?

I have a container of Clinique powder and it seems like I've had it forever! I would say at least 6 months if not longer...I was just wondering if it should be replaced or if it is ok to use for so long...as in bacteria or anything getting in the powder. The container is still at least half full too! ThanksHow long should you keep powder foundation?
I use a fresh cotton ball every time I apply so there is ot a bunch of facial oils going back on there from the little poofy deal that comes with it. Then it will last longer.How long should you keep powder foundation?
I would probably buy me a new one. What I do, is I usually ask the sales person about how long the product would last and the minute i go home i use a label machine and put an expiration date on the product. If I bought it sept 07 and the shelf yr is for a yr the I label the product sept 08. This is an easy way to remember and with some many products that we buy is hard to remember them all.
as long as u want 2
its should have a sell by date. if you look at the back or bottom it should have a little picture of a container and inside will say either 6M or 12M or 18M or 24M which is the amount of months it will last! its on the back of most beaui products and shampoo!!!
I buy a new one after about a month. And change your cotton ball everyday to start the day fresh!