The Floating License Server holds the license and serves a license (concurrent key) to each user based on availability. However, GeneSpring can be installed on many more systems than there are concurrent keys associated with the floating license. GeneSpring can only be used simultaneously by as many users as there are concurrent keys.
The error 'No License Available' is shown, if an additional user beyond the number of available concurrent keys is trying to start GeneSpring. For that user to be able to launch GeneSpring, one of the existing users has to shut down GeneSpring, which will release a concurrent key that can then be assigned to the new user by the Floating License Server.