Attempt to free the key from the sleeping guard. Make sure to wait whenever a message appears stating that it seems dangerous to continue. After two or so attempts, she'll tighten her grip on the key. Then use erotic command, while still waiting at every warning message. Eventually, her grip on the key will loosen. Use the Free command to take the key.
Thank you so much. I just completed it and I really enjoyed it despite it's length. I really enjoy games with heavy in-combat sex. This is the first I've seen for Android which is currently the only platform I can play thess games on. I really appreciate that you've been able to make a fun game on that platform and I can't wait to see what you do in the future!