Should I just install some new free version and again upgrade to the Pro version of 18.104.22.168 ? And of course pay again for that new Pro version ?
There is no new Pro version. As I said in reply #1, It is now just Fences. There's no Pro.
You got free updates through version 1.9xx. Version 2 and up would be an upgrade.
When you buy a standalone version, you get free updates up to the next version number. Version 3 would be a paid upgrade. Possibly at a discount, since you did purchase Version 1.