We can't promise 100% ban free accounts.
What we can say is that after 22 months we have been working with these accounts, none of them have ever been banned. We do collect Dragon Stones via daily logins, and we don't sell duped accounts like the ones which were the main reason for the ban wave in 2017. The farmed accounts are modded with a special script, which has been optimized to output very safe accounts. Farming definitely gives the accounts a higher chance of getting banned, but we are not aware of any account suspension because of modding outside the World Tournament. The World Tournament is totally safe to play with our accounts as long as you don’t use mods on your own.
So we are very confident to say that our accounts are very safe, but even after thousands of sales, we still can't promise that they won't get banned in the future.