If this patent ever becomes an actual product feature, Instagram can charge its users a fee for adding links to photo captions. The patent application Instagram's parent company Facebook filed back in 2016, displays a pop-up that would appear when a user adds a URL to a caption. It asks you if you want to pay $2 to make the link live.
Titled "Adding paid links to media captions in a social networking system," the patent describes how the system would function: "If the online system detects the text content of the caption includes a string of link text identifying an address, the online system prompts the posting user to pay a fee in exchange for generating a link."
Since it's beginnings, it isn't possible to link a story, product, or other URLs in captions of photos. So, users have to add links through their bio or Instagram Stories (at least for verified users). Of course, getting users to pay for this feature is an entirely different question. But it will open up a new way for the social network to generate revenue. However, we do have to remind you that patents don't always become final products. At the very least, it shows us what the company is thinking about releasing on the app.