Driving for pay in a personal car puts the vehicle to a different use than commuting or errands, and the contract's use language may treat that differently. The question of what counts as paid use is easy to answer wrong after a claim is filed, so settle it on paper before you buy.
Find the use definition
Look for the section that describes personal, business, commercial, or passenger-for-hire use. Some forms define these terms in their own section, while others leave them to a line in the eligibility or exclusion section. Write down the exact words. If the form does not define paid driving, ask the provider how it would classify delivery or passenger work before you assume it counts as personal use.
Count the miles that change the picture
Paid driving often adds miles fast, and mileage limits on a form usually count the total on the odometer, not only the personal trips. Ask whether miles driven for pay count toward any cap, whether a limit applies at purchase or through the life of the contract, and what happens when the odometer passes the limit during the term. Keep your own log of personal and paid miles so you can answer the question with records.
Ask about notice and proof
Some forms expect you to tell the provider when the car's use changes. Ask whether that duty applies to you, how to give notice, and whether late notice can affect a claim. Ask what records the provider may request, such as trip logs, app statements, or registration papers showing how the vehicle is used. Know which of those papers you already have before the question comes up.
Keep the app's paper separate
A driving app may carry its own insurance, and that insurance is not a service contract. Read whatever the app provides, and do not assume it fills a gap the service contract leaves open. The contract and the app's policy answer different questions, and any gap between them is yours to find before a breakdown.