From that site ;
"Total Commander is a Shareware program. This means that you can test
it for a period of 30 days. After testing the program, you must either
order the full version, or delete the program from your harddisk."
If the laws in your country forces you to obey that, you can only use
it for 30 days.
But most countries have no such law. In my country this is considered
freeware legally, as the owner of the program allows free download and
the program keeps on working as before.
If you reboot once every three months you have to do four extra clicks
per year, not much of a nag for such a valuable program.
It is actually a smart way to sell the program. The low nag factor
allows millions of people to use the program and they learn to love it,
and one day they pay for it, maybe not mainly to get rid of the nag
screen but to give something back to Christian Ghisler who has created
the program and made it so easily available for everybody in the world.
A successful program must have a pyramid of users, where the top of the
pyramid pay for the program, the lower parts of the pyramid are using
it for free with a nag factor. Users from the lower part of the pyramid
are moving up, becoming regular users of the program, getting used to
the idea of paying for it. Millions of new users are attracted to the
base of the pyramid because the entry is free.
I don't think that people on high horses, like yourself, is adding
anything valuable to this situation.