The doublejack token was minted on the Stellar blockchain, and all fees associated with the token are covered by the token sale.
This means that there are no fees for holding the token. When it comes to selling the token in the future, there may be a small swap fee to cover the blockchain network fee for the token swap. The current network fee for Stellar is 0.00001 XLM (Stellar Lumens), which is equivalent to about $0.0000025 USD at the time of writing. This fee is used to compensate the network validators who process the transaction.