An application stops working after 30 days and then prompts the user to input some...

The CompTIA Tech+ Study Guide (Exam FC0-U71, 3rd Edition, 2025) explains that software requiring activation often stops working after a trial period—typically 30 days—until a valid product key is entered:

“Activating software is a different story—you have to do it. Either you will need to enter the product key before the app will work the first time, or it might work for a few times for free then ask you to activate. Some products… include activation features that lock the installed copy… Usually you have 30 days to do so, or a certain number of uses, before it stops working.”

This clearly identifies a product key as the required input to activate or continue using the software.

Verified Reference:

Chapter 5: Software Applications — “Registering and Activation” (pp. 288–290).