Yes, a cat camera collar can have a built-in memory; however, you must add a memory card. The built-in memory usually has a little capacity, and it's best to insert your memory card. The majority of the cameras allow a memory card of up to 32 GB; if you find a 32GB has a big storage capacity, you can go for a lesser storage capacity memory card. Still, get a memory card that is fast and reliable so that you don't lose any of your data.