if its skincare products, i try to use them before the expiring date. But i also use them after the expiry date.. i think the date is just an indication like food and u should judge for yourself whether u feel they are not safe to use anymore. Except for products that oxidizes (fast) like sunscreen, vit C, retinol.. they will do more harm than good if you use them after the expiring date.
Same for makeup products, i have some that are passed their expiry date… thats why I have only bought one make up product this entire year. Need to finish the others before i will allow myself to buy new ones.
I store all my skincare and makeup items in drawers in my desk so its not exposed to light or humidity to keep them last longer.