They certainly won't still be worms after 'weeks' - bloodworm is the larvae of a midge, so those that don't die with turn into bugs!
It's best to buy bloodworm fresh in small amounts, just enough to last a couple of days then buy more as you need it. It doesn't store well at all without a lot of hassle.
The other option of course is buy it frozen and defrost it as you need it. Most fish don't even notice the difference if the tank has a bit of current to make the worms move around.
yeah i feed my fish frozen and it seems to help if you dump them infront of the water retuwn on your filter, atleast for me...that way they all scatter real quick. then i ussually turn my filter off for about 3 mins til all the food is gone