Storage ciondition of reference standard of API versus Real-time storage

Dear All
Can somebody explain why reference standards of API are stored at 2-8 deg C when a long term shelf life (3o deg C; 65% RH) of that particular drug is established already as 5 years?
What is the logic behind this storage condition of reference standard followed by most of the companies?

No need to store, every API reference standard at 2-8 deg c. It Depends on the storage condition of marketing product…Either it is 2 to 8 or ambient condition. Same conditions to be used for reference standards…

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