For security reasons, there are restrictions on how you can spend NX. Each game has its own specific set of restrictions. Below are the restrictions for Mabinogi.
First purchase trade restrictions
When you buy NX for the first time, and certain criteria are met, a 4-day restriction timer starts on the account from which you purchased the NX.
If you purchase an item in the Cash Shop anytime during this 4-day period, your account is restricted from performing some trade-related actions in-game. You are immediately notified in-game if you initiate any restricted trade actions.
This trade restriction is removed automatically after 4-days have elapsed from the time of your first NX purchase.