Definition
Used to indicate that an action will be performed or a request will be granted only on the current occasion.
僅此一次
I don't usually do this, but I'll make an exception just this once.
我通常不會這麼做，但這次我會破例一次。
Just this once, I will help you finish this task.
就這一次，我會幫你完成這個任務。
I'll agree to your request, but just this once.
我會同意你的請求，但就這一次。