It's a SAAS solution we offer (software as a service). Meaning that you would simply concentrate on running your site, and that alone. When you click on upgrade, it just does it. You dont need to think about what PHP versions things are running etc. The pricing you can find here
https://invisioncommunity.com/buy
Note, we can of course get you over there free of charge if you decided to go in that direction, and may even be able to offer credit for your self hosted license if you wish.
Feel free to reach out directly if you have any further questions.
This is a prime example of what I mean by "hosting issues". We know people who run communities, want to do just that, and not mess with the hosting side of it.