FMP and FMP Advanced can host 5 concurrent (at the same time) clients.
Clients can be FMP or FMP Adv or FMGo.or Webdirect
More than 5 concurrent users would require FMP Server.
FMP Server would purchased or paid Monthly - users monthly are sold in blocks of 5 concurrent users.
About FMP 13 Links Filemaker 13 Links On Release Day