you can play from different computers, that's not an issue.
The problem happens if you've done free ad sponsors from multiple computers.
The way I understand it, is:
You play Ragnarok from computers A, B, and C. This is fine.
You vote for ad sponsors on computer A. This is also fine.
The problem happens if you also vote for ad sponsors on computer B. The system knows that ads have been voted on from A and B, and once it sees that the same RO account has also logged in from computers A and B, then it knows that the same person has been voting from multiple locations, and you get banned.