One more thing to add for everyone who considers purchasing this:
There is a reason why the upgrade-DLC to version 2 is as expensive as the original V1 program, and why both version 1 and version 2 can still be purchased on the original developer's website:
Version 1 is mostly static flow visualisation, but version 2 adds dynamic playthrough to the flow, allowing logic switches to be checked and parameters to be calculated based on variables and so on.
If you don't need those additional functions (and a few more that had been added with V2), you can still use the cheaper V1
Most small games can probably go by with V1, the dynamic flow checking is good if your game has complex relationships and story-branching instead of mostly linear or static flow with only secondary quests branching.