The process of placing an item somewhere and remembering it later requires 'working memory' to hold the action long enough for the hippocampus to 'encode' it into long-term storage. In ADHD, this encoding process is heavily dependent on dopamine levels and conscious attention.
Because the act of setting down keys is completely mundane (low dopamine), it fails to trigger the neurological "save function." Furthermore, the ADHD brain is highly susceptible to 'proactive interference.' The moment you cross the threshold into a new room, the deluge of new visual information overwrites the fragile contents of the working memory buffer. The memory of the keys is dumped to make room for the new environment.
Additionally, the ADHD motor cortex frequently outpaces the prefrontal cortex. Your hands move before your logical brain registers the action. This disconnect means your body acts autonomously, placing the phone in the fridge while your brain is entirely occupied simulating a conversation you plan to have tomorrow.
