A floating license / concurrent license allows multiple users to share the use of an application. A single floating license can be used by a number of concurrent users. The Floating License Server holds the license and serves licenses to the users based on availability. The number of concurrent keys has to be specified at the time of purchase. This number determines the maximum number of GeneSpring applications that can be run simultaneously.
 
For example, if you have purchased a floating license with two concurrent keys, GeneSpring can be installed on multiple systems (more than two) but GeneSpring can only be used on two machines at a time.