You don't
To get the lift key, talk to one of the Rocket trainers you have already beaten. He will drop the key, then you can pick it up.
use the lift key to use the lift
The lift key is the key to operate the lift in the underground base of Team Rocket in Celadon City. The key can be obtained upon defeating one of the Rockets inside the building. You will need to the key to go to Giovanni, the boss, and when you defeat him, you will obtain the silph scope.
You can find the Lift Key in the Team Rocket Hideout on Pokemon FireRed. It is dropped by a Grunt on basement floor 4 after defeating him.
You don't
To get the lift key, talk to one of the Rocket trainers you have already beaten. He will drop the key, then you can pick it up.
use the lift key to use the lift
The lift key is the key to operate the lift in the underground base of Team Rocket in Celadon City. The key can be obtained upon defeating one of the Rockets inside the building. You will need to the key to go to Giovanni, the boss, and when you defeat him, you will obtain the silph scope.
You can find the Lift Key in the Team Rocket Hideout on Pokemon FireRed. It is dropped by a Grunt on basement floor 4 after defeating him.
In the game corner you'll beat a man the the lift key will appear next to him. Hope this helps.
You have to battle all those Team Rocket grunts first. The Last One will drop the lift key.
You use it on the lift (1st Floor) to get access to Giovanni. This is your first battle with Giovanni.
You get the Lift Key on B4F when you battle a Team Rocket Grunt in the far north corner. He even says "Who has the Lift Key" before the battle begins. He has a Level 21 Zubat and Koffing. Once you defeat him, then he will drop the key.
In Pokemon Yellow, the lift key is in the Rocket Hideout under the Celadon Game Corner. One of the Team Rocket Grunts will mention the Lift Key before you fight him. Once you defeat him, he will drop the Lift Key. He should be in the northwest room on the 4th floor down (B4F). To get to the Rocket hideout, you need to use the switch behind a poster.
you can not
The lift is on basment floor 2 but the key is on basement floor 3.