You need to be more specific. Lots of security-conscious apps wipe their memory. Memory contains, among other things, the decrypted text and private keys for the app. RAM is known to hold data longer than you'd want, and it can be swapped out onto persistent storage like the internal SSD. If you don't know that wiping memory is a basic and common feature for apps like this, then you're not qualified to have an opinion. Now if you think wiping the memory is ineffective, inefficient, or superceded by a bigger issue, then we might have something to talk about.