Never long term store weed in anything plastic/mylar.
Get an airtight glass jar that is close to the size of weed you're storing, buy a cheap hygrometer from ebay, pop it in the jar.
If it's around 58-62% relative humidity then don't bother with Boveda packs. If it's less or more throw one (8g Boveda 62% pack) in per 14g of product.
Keep the .jars at around 18 degrees.
As soon as the RH on the hygrometer reads around 60%, take the Boveda packs out. They have a tendency to remove the terpenes from the weed.