If they are whole they probably don't need to the sniff test, but sniff them anyways and if they smell like nothing and are not rancid, then use them. If they are ground they will go rancid faster, so sniff them.
We grind them in a coffee/nut grinder, mixed with ground flax seed, and put a tablespoon or two with our oatmeal or grain flakes. They have a nutty flavor and lots of omega 3's.
Another option, to use them whole, is to make a chia pudding. Generally, some kind of milk (plant based or dairy), cocoa, sweetener, vanilla, and chia seeds, let sit in the fridge overnight, and voila a chia pudding. We've had it twice, the chocolate was better than the vanilla flavors.
A substitute for an egg: It’s simple – just 1 Tbsp chia seeds + 2.5 Tbsp water = a chia egg. But then what? So many uses!
https://minimalistbaker.com/make-chia-egg/
When I'm low on ground flax in baking, I'll use ground chia seeds.
Except for the pudding, I like them ground. After I grind them I keep most of it in the freezer and just a serving shaker for daily use.