Updating to Passolo 2018 (for testing) while still using Passolo 2016

We are using Passolo 2016 for our product localization. We also would like to test Passolo 2018 on a test computer to see how it works and if there are changes. We can easily transfer the license between two computers running the same Passolo version.
In 'my account' there is a notification about upgrading the license. Is the license transferrable between the two versions 2016 and 2018 and back to 2016? Has anyone else tried this?
Thank you