FWIW. There is not a big difference between version 2017 and 2018, graphicwise, they both use the same ‘graphic engine’
The difference between 2016 and 2017 was much larger, due to the loss of the ‘hardware acceleration’ choises in previous 2017 versions.
They even came up with some patches for flaky (graphicwise) systems in version 2018, so, in theory, the 2018 version should perform better.
In general, if you have a network and someone decides to activate a new version by entering the serial and code, a 60-days grace period starts.
If you do not remove that activation, all users must activate the new version.
With a network, you can only have one active version for all.
For testing purposes, one could install the trial version. The trial period of 30 days is usually enough to decide if you would activate it.