noun (n)

• someone who expresses strong approval(noun.person)

  Synonym:
  endorser, indorser, ratifier
  

  source: wordnet30
• someone who contracts to receive and pay for a service or a certain number of issues of a publication(noun.person)

  Synonym:
  reader
  

  source: wordnet30
• someone who contributes (or promises to contribute) a sum of money(noun.person)

  Synonym:
  contributor
  

  source: wordnet30
• One who subscribes; one who contributes to an undertaking by subscribing.(noun)

  source: webster1913