What do we call an establishment that provides services on a regular or irregular basis?

The term for an establishment that provides services on a regular or irregular basis is "Facility." Facilities are defined spaces specifically designed to deliver services or support various operations, such as healthcare, recreation, food service, or education. They can vary in size and scope, and they serve as specific locations where services are rendered consistently or intermittently, depending on the needs of the community or clientele.

The other terms, while they may suggest locations where services are provided, do not universally encompass the broad range of establishments that can offer services. For instance, a Service Center typically refers to a place focused on providing specific services, often related to customer support or maintenance. An Operation Hub usually connotes a centralized location for coordinating various activities or logistics rather than serving clients directly. Lastly, a Workshop generally indicates a space for hands-on work or training, which may not necessarily fit the definition of providing services on a regular or irregular basis in the same way a facility does. This makes "Facility" the most fitting term for this context.