The cost of maintaining a trading position is often referred to as the cost of carry or carrying charge.
It can come in many forms, including interest on margins or the loans used to make the trade or the cost of storage and insurance associated with holding a commodity.
In forex, there are several costs that can arise from keeping a position open.
Changes in interest rates can require a charge on your account, or overnight funding charges can be incurred.
Often, the cost of carry will already be included in the price of opening a new position. Usually, it varies depending on the type of trade and asset being traded.