User blog comment:SunYunBun/Craft Essence Debate/@comment-24050152-20160407082100/@comment-27247829-20160408055124

Just use the chocolate on the CEs that you put on your most often-used Servant; I use them on DB2016, but that decision is up to you.

As for the memories, I think you can relive it at the Menu, right? Just use it either way; when someone struggles a lot to make you a handmade chocolate (or buy you a cheap one in Mordred's case), you are expected to eat it; cherishing it until expiry date only taints that hope. CEs are still your personal weapon anyway, so there's no problem with it.