What concern arises from the development of non-display application use by vendors?

The concern associated with the development of non-display application use by vendors primarily revolves around the potential for vendors to implement usage-based charging models. This is based on the idea that as applications evolve to be integrated into back-end systems or automated processes without a user interface, vendors might capitalize on this by quantifying and charging for each instance of application use. Consequently, this creates a financial implication for businesses relying on these non-display applications, as previously included costs in a flat-rate model could now lead to unpredictable expenses based on utilization levels.

While other concerns such as support termination, data access limitations, and product availability do exist, the immediate worry from a financial standpoint lies in the potential for increased costs enforced by usage metrics, thus making the correct choice pertinent in highlighting the financial implications vendors may instill through charging mechanisms.