Where is the key item to open door at canalave city without a member cards?

You can't open the door in Canalave City without a member card. The door is specifically designed to be opened only with a member card, which is acquired by completing the Gym Leader's challenge in Canalave City.

If you are trying to access an area in Canalave City that requires a member card, you need to:

1. Challenge the Gym Leader: Defeat the Gym Leader, Byron, in Canalave City's Gym.

2. Receive the Member Card: Upon defeating Byron, you will receive the Member Card as a reward.

3. Use the Member Card: Now you can use the Member Card to open the door and access the area.

There is no other way to open the door without a member card.