We don't use SWIM here, please read the BLUA and OD Guidelines (both links found in my signature) before you post again to get a feel for our community. Take advantage of our state of the art search engine, our database spans a decade and counting, so chances are, your questions have been asked (and answered) before.
Welcome to Bluelight!
P.S. You should read the OD Posting Standards as well, it will go into further detail on how to compose your posts in a way that will allow us to answer your questions to the best of our ability. For example, at the very least, it helps to mention the drug you're asking about. We have no idea what "this stuff" is, so there is really no way any of us can give you advice on proper storage. You marked (amphetamines), this could mean anything from crystal methamphetamine to amphetamine sulphate, or even pharmaceutical amphetamines such as Adderall and Dexedrine...
In general, amps like to be stored in a cool, dry, airtight, opaque / light-resistant containers.