This comprehensive tutorial explores the integration of PubNub with Ethereum blockchain technology to create a smart contract-based subscription service. The application is powered by a private Ethereum blockchain using Solidity, with the Truffle framework and Ganache to simulate and log transactions. Users can subscribe to a service via a web app, which utilizes smart contracts to enforce subscription rules across multiple business entities. PubNub plays a crucial role by sending real-time notifications of contract execution, enhancing the user experience by providing instant updates on transaction statuses. The tutorial provides a step-by-step guide to setting up the necessary software, compiling and deploying smart contracts, and testing the application, highlighting the potential of blockchain and smart contracts in transforming digital transactions and business processes.