No, you don't necessarily need to purchase a blockchain node to use distributed identity. Distributed identity solutions can be implemented using various technologies and platforms, some of which may not require you to run your own blockchain node.
For example, some distributed identity solutions are built on top of existing blockchain platforms like Ethereum or Hyperledger Fabric, but they provide APIs or SDKs that allow developers to integrate these solutions into their applications without needing to manage the underlying blockchain infrastructure.
Additionally, there are also cloud-based solutions that offer distributed identity services, such as identity management platforms that leverage blockchain technology. These platforms handle the management of the blockchain nodes and infrastructure, allowing you to use distributed identity features without having to purchase or maintain your own nodes.
In the context of cloud services, Tencent Cloud offers a distributed identity management solution called "Tencent Cloud Identity and Access Management (IAM)". This service provides a centralized way to manage user identities and access permissions across multiple cloud services and applications, leveraging blockchain technology for enhanced security and decentralization. By using Tencent Cloud IAM, you can benefit from distributed identity features without the need to purchase and manage your own blockchain nodes.