Synonyms for Subscriber (same or very similar meaning)
WordNet sense 1 (someone who expresses strong approval):
endorser, ratifier, indorser
WordNet sense 2 (someone who contracts to receive and pay for a service or a certain number of issues of a publication):
reader
WordNet sense 3 (someone who contributes (or promises to contribute) a sum of money):
contributor
From the ODE community, based on WordNet
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