All the prices are One-off-prices for version 1.x of the Plugin license — unlimited updates when new features become available.
The License is valid for both Mac and Windows platform.
For server installs, you can use your regular license. The license counts for runtime users connected to the server. i.e. the single developer has 5 runtime users. The license is valid for a server with 5 users connected.
A single pack of runtime license can be used at a customer site who only runs your compiled ACF functions. You need a developer license to compile the packages, and distribute binaries to users who only need runtime.