FDS Express does not have any connection limitations. With FDS Express you can run no more 1 CPU per application (this allows multiple applications per CPU) with no connection limitations. As your application requires more than 1 CPU for reliability or scalability we have a mid-level FDS offering.
Here's the relevant section from the 2.0.1 license.
3.1.3 Adobe Flex Data Services Express License. This Section 3.1.3 applies only if Licensee has obtained a valid Adobe Flex Data Services Express Software license. With respect to each unique application created by Licensee, Adobe grants Licensee a license to install and use such unique application and the Adobe Flex Data Services Express Software as Production Software on a Per-CPU basis; provided that Licensee shall not: (a) install, use or access such unique application and/or the Adobe Flex Data Services Express Software on more than one CPU, (b) cluster any CPUs, and/or (c) use load balancing. For avoidance of doubt, Licensee shall not deploy any unique application on multiple disconnected single CPUs, including without limitation, on kiosks and other such devices.