The problem with pollen is that it is hard to keep for more than a year. It becomes inviable. If pollen gets ANY moisture in the container it's in then it's inviable.
I would suggest putting pollen in good ziplocks with all the air pushed out. store it in a dry dark place that aren't subject to major temperature changes. Freezing pollen is okay but you have problems when you take it out of the freezer the bags condensate on the inside. And can make your pollen inviable.
This is one reason why you dont' see seedbanks selling pollen. It's so darn hard to store because of it's short shelf life.