Every service for chainlink is paid for using their native LINK token.
It is the utility token that underpins the services offered.
For a cursory look at their economic model see below.
https://chain.link/faqs#what-is-chainlinks-economic-model
LINK is a cryptocurrency that is a vital part of the blockchain technology being offered.
The work that chainlink labs has done and has implemented for tokenizing securities, enabling high fidelity data providers and automating audits of financial markets.
Immutable smart contracts are useful but if needed to interact with the outside world only as secure as the weakest input, chainlink labs have done a lot to solve the oracle portion of the blockchain trilema.
This will enable self executing contractual agreements that are mostly B2B & have wide sweeping implications for finance.
This is not a fluff project it is very serious and has real scientists pushing inovation.
Here are some use cases
https://blog.chain.link/smart-contract-use-cases/
Research https://chainlinklabs.com/research
I suggest reading the white paper 2.0 first
Wont happen legacy systems more complicated than expected, well it wont happen functionally....
Its a stochastic process