Ok, I assumed you were using HS4. Because you were referring to the instructions on the HomeSeer forum of the HS4 version of the plugin. Either way, you have the correct version now.
You should have gotten a 30 day trail. Sometimes HS3 is confused and thinks they are already used up, so you can request an additional 30 days from HomeSeer. Purchasing is also a solution, thanks!
The power value is now a (child) device of it's own, so you can use the "a device value is..." trigger instead. But you will have to change that manually for all events, sorry!
Off course you can still go back. But I suggest you make a good backup of your system and give it a try!