Stardock have never sold licenses which allow free upgrades to every future version.
Standalone Licenses are always for the version you have purchased which in this case seems to be the 1.x series. Your license continues to be valid for this version and all versions in the 1.x series.
There are significant enhancements in v2 and v3 over v1 which is why they were a non free upgrade.
For example depending on the version there is KVM support, encryption, drag & drop for files, file copying (I can't recall off hand if MP1 clipboard supported files or not), audio sharing, later OS support, unlock secondary support, hotkeys etc.
There is a 30 day trial available should you wish to try it and see if the additions offer any value to you and make upgrading worthwhile.