How long can you kept hamburger meat after open it.?

Raw hamburger should be used within a couple days, though it could stay good longer. It is best to freeze raw meats if you are not going to use them for a few days. Safeness really can't be determined without lab tests.

The best policy for hamburger is to use common sense -- first if you are in doubt, throw it out. Failing that, smell it carefully. If there is any "off-normal" scent, throw it out. Second, if you decide to cook it, cook it thoroughly, meaning no red showing inside. Kill every last bacteria, and wash your hands and cooking utensils thoroughly. Lots of problems start with failure to wash hands, and for that matter, anything else the raw meat has come into contact with.