Three A4 PDF sheets. Print them, stick them on the fridge and let them remind you what needs finishing.
A table for your fridge door: what you opened, when, and when to finish it by. With times for the most common products.
21 labels to cut out and stick on jars, pots and leftover containers.
FreshyWith Freshy you note when you open a pack and the app reminds you before it goes off.