Streaming channels have various business models and ways to watch. Here's a brief overview of commonly used terms and their general meaning.
Rent a film/show on a streaming channel usually allows consumers to stream as often as they want but for a limited time, typically 24-48 hours after they start watching.
Buy a film/show usually grants the consumer an unlimited streaming period on that channel. Sometimes channels allow Download to own, where the title is downloaded to the local computer/device, often in a DRM protected format.