If your active key and your memo keys are the same and you have shared your private memo key, then your account is still vulnerable.

Say for instance, I created a website and asked you to enter your private memo key, I could then transfer your funds. That’s because your memo private key is the same as your private active key. Active keys give you the right to buy/sell/deposit/withdraw funds.

The owner keys provides this same access in addition to changing your password.

My owner, active, and memo keys were the same, so I changed my owner and active keys. Afterwards I can continue to read my memos on previous transactions.

As an alternative changing your keys, you could just create a new account and then transfer your assets from the old account to the new account.