Is it necessary to pay for the Professional Version every year once you pay the initial cost of the Professional version?
Also, I was warned not to let any cleaner program change the register or its contents. Will Professional stay away from such changes?
Thank you
The professional features within the programme will keep working after a year.
What you lose if you don't pay again is the ability to get direct support from Piriform by raising a support ticket, and I belive that automatic updates also stop.
You can still get support/advice from other users on this forum, just like with the free version, and will still get notification of new versions to install yourself (and they will still be Pro).
The registry cleaner is still there in Pro - Don't use it; it is not necessary with modern computers and may even 'break' them, especially Windows 10.