subscriber

noun

1. A person who subscribes to a publication or a service.

   “Our magazine has over ten thousand subscribers.”

   “The aim is to better appeal to the varied interests of Netflix’s sprawling subscriber base. […] “All signs point to Netflix having reached escape velocity, with subscribers scaling far faster than investors expected,” Mr. Greenfield said.”

2. A system or component that subscribes to something, such as an event, made available by a publisher.

   “An event aggregator facilitates a fire-and-forget model of communication. The object triggering the event doesn't care if there are any subscribers.”

3. A person undersigned.

   “Near-synonyms: signatory, signer”