If you tell the truth, you don’t have to remember anything.
You can see this as extreme as you personally want but fact is: The more you speak the truth, the less problems your brain will have in conversations. Always thinking “Shit, what am I allowed to talk about” is stressful and a lot of work. Don’t make it so hard for you, just be honest and don’t lie around. There’s nothing wrong with making mistakes or not knowing things, but there surely is something wrong with lying about is as long as you can.