A Pro license is valid perpetually and includes all application updates for the same major release version. For example, buying a license for 18.104.22.168 gives you the right to use all 1.x.x.x versions. Additionally, from within 12 months of purchase date, you're eligible for all updates, even for major releases.
You may use a Tablecruncher license on all the Macs you own. So, if you own an iMac and a MacBook, feel free to use a single license for it. Companies need a license for every employee using Tablecruncher, however.
The CSV Viewer mode will be free forever and can be used without any license credentials.