THere has to be a date on the package
Packed /use by date so check if there any on the packaging
*its normally 3-6months if its well sealed pack and in storage conditions , but depends on conditions like humidity and so on ,
if you not sure on normal conditions, cover with a dry polethene bag/ bags air tight. and avoid contact from floor/ walls -use wooden planks covered with polythene too. out of water and wetness, im sure you can keep more than 2 month in that way.