Any game time, PLEX or DLC packages that are purchased from the Steam Store will always be delivered to the EVE Online account that was automatically created when EVE Online was added to the Steam Library. This account will automatically appear within the account list of the launcher when the game is started through Steam, usually starting with "STEAM::", followed by a number if no account name was assigned.
It is not possible to have these packages delivered to any other account.
If the game was added to the library before June 2013, then no EVE account is tied to the Steam account and purchases can not be delivered. A ticket to Player Experience will be required to resolve any purchases made through Steam for these accounts.