Provided your code came from Adobe itself, then putting it into your account should add on, i.e. extend, the expiry date of your current plan. If you have any issues with that, e.g. it does not work, you would need to contact Adobe directly as this user forum has not access to accounts.

Note: Please do not respond to any requests by Private Message in this forum for account information. Scammers are known to do that, sometimes posing as Adobe.

Dave