Hello
I used to make my own, just a batch to last a week.
Suppose they would last longer if in an airtight container.
My ones consisted of protein powder, peanut butter, honey, oats, drops of vanilla flavouring, raisins and sometimes sunflower seeds.
Mixed up, into greased tray, into fridge then cut up the following morning and wrapped in greaseproof paper.
Tasted pretty nice.
Gary