Can a single license be shared on multiple machines ?

[jdewindt]

Yes it is possible, depending on the license type.
A purchased license is installed in your Scenario Navigator database. When multiple Scenario Navigator clients (possibly from multiple machines) share the same database server, then a pool of licenses is created. The scenario Navigator license model presentation in the attachment details this concept.

Also, please refer to the online manual for more details: 3.1.5 Licenses or complete manual