Do I need to repalce key ignition?

Given that it has been working this way for you, why open up a can of worms? This is a GM thing with their anti-theft systems. They cause more trouble for car owners than they do for car thieves. The difference is thieves know how to bypass the systems. Car owners get stranded. Your mechanic was conscientious enough to point this out so you can have it fixed before it becomes a problem for you, but since you know it hasn't been getting worse, you may elect to trust that it isn't going to get worse in the future and leave you sit somewhere.

What you SHOULD do though is not make the mechanics go through this hassle when they're trying to work on your car. Do them the courtesy of telling them about the ignition switch or anything else they need to know to get your car into the shop. Part of their job is to look for things like this so they can prevent future problems for you. Many people would get angry if they had an ignition switch problem that the mechanic saw previously and he DIDN'T say anything. Customers get angry with us when we supposedly try to sell them things they don't need, and they blame us when something breaks and we didn't use our psychic powers to warn them ahead of time.

Nope. In my first paragraph I said leave it alone if it hasn't caused you a problem or gotten worse in seven years. It's the mechanic's job to point out things like this but he has no way of knowing that you've been getting by this way. He likely thought you weren't aware of the issue.

Wow. What an attitude. Where in any paragraph did I say you had to get it fixed? What I said there was it is a courtesy to inform your mechanic of ANY issues out of the ordinary so they don't need to point them out to you.

This is exactly what you asked:

"What would be your advise pertaining to this situation?"

Now you want a yes or no answer and you're angry that I gave you the advice you asked for. Okay. Get the stupid thing fixed because, well, ... I don't know why but you're concerned enough to ask. If you knew there was a problem, why did you wait seven years to inquire about fixing it?

There IS no yes or no answer to this because YOU are the one who is in the best position to make the decision. You already know it hasn't caused a problem in seven years, so why are you worried now? So don't get it fixed, like I said in my very first sentence in my first reply. Why spend money on something that you've been getting by with all this time? You asked for "advise", (advice). You didn't ask for a "yes" or "no". Don't blame me for trying to help. You're just looking for someone to be mad at. If you reread my replies carefully, you will see I never said to have the repair done. If you read something else into what I typed, copy and paste it here so I can read it and clarify what confused you.