Shelf Life if Hi-Tek Powder

[Taterhead]

Is there an expiration date for the powder form of Hi-Tek? Assume stored in garage condition (hot and cold extremes), powered, in the original container.

Yes, indoors would be better, but trying to not look a gift horse in the mouth. What are signs that it has turned?

[Ausglock]

I have Hitek powder dating back to 2015.
Used some a few weeks ago. No problems at all.
It is a bit darker when baked, But still adheres and shoots great.