If the engineer is able to resolve the problem or carry out the repair, but is only prevented from doing so by the customer requesting the engineer not to proceed with the work, then the customer is charged for the engineer's time spent to that point.
If the engineer is able to resolve the problem or carry out the repair, but is only prevented from doing so because the customer does not possess the required software or Product Key, then the customer is charged for the engineer's time spent to that point.