Hi, Terri, welcome to Discuss Cooking, tou'll like it here.
Sure you can freeze them or keep them in the fridge for a week. The 'must use them immediately' line is a bit extreme. Of course, some nuts (those with a higher fat content) wil turn rancid faster than others.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan