Just for the record, it's the BOS (Entity Service) which acts as an application manager to support multiple DevForce client applications in an n-tier environment. The Entity Manager is the client side caching and management class.
If your product license allows it, you can have essentially any number of client computers connecting to your BOS. A common Enterprise license allows 10,000 concurrent users (logins from client applications). Check your license, or talk to your Account Rep if you have any questions on what your license allows.