Not of an external memory system, no. This would be internal. But would you call it "an internal memory system", or "decreased growth in reaction to sunlight"?
Another option: (micro-)evolution. Is an amoeba's resistance to a chemical "memory", or an environment-selected random mutation? Again, technically it can be viewed as memory, but it's diluting the term so far as to make it a catch-all for any kind of information, ever, to get someone to click on a link.
> But would you call it "an internal memory system"
Well, it's not being used later on to make decisions, is it?
I suppose I will go with that for my definition of memory: the agent makes a change to the state of the world (external) or to its own state (internal) and that change later affects its action.
Using that definition, my answer re the amoeba is yes.
I can see why it seems too broad. But I don't know a better definition. I suppose one could stipulate that consciousness is required. But I don't think that would be a standard position.
Another option: (micro-)evolution. Is an amoeba's resistance to a chemical "memory", or an environment-selected random mutation? Again, technically it can be viewed as memory, but it's diluting the term so far as to make it a catch-all for any kind of information, ever, to get someone to click on a link.