Tab: Business > Cart. This row has no friendly label in the current version, so it shows its internal name oneTimeFee. Default: 0. Global only.

It is the amount of a One Time Fee that is added to a customer's very first order when the One Time Fee ordering module is configured for your account. Customers who have already paid it are not charged again. Leave it at 0 (or do not enable the module) if you do not charge a sign-up/first-order fee.