Most of these programs are for "buy". They will let you download a trial verson, then after a couple of days, it stops working unless you pay for it. I don't know if this one you mentioned is like this or not.
Scam ! A friend of mine had just brought a computer and just to see what would happen they installed my clean-PC and it turned out that it said the computer had lots of viruses, trojan, etc. It said it needed to be cleaned out. Now you tell me, How is a brand new computer, Never been used, gonna have all those Viruses? They just want your money. A Free cleaner will do the job just as well.
Avoid. Along w/ the scam issues above, allowing third party access to your computer & personal info is very risky now. You don't know who these companies employ & if they're all honest people. It's not worth it to find out the hard way, your ID & bank/credit card info compromised. If you use Windows & your computer is running slow, simply type "Disk Defragmenter" in your Windows search box, bottom left of your computer screen. (Click on the "Start" button to begin.) Then click on the words "Disk Defragmenter" under the "Programs" list that appears. Follow the prompts. This clean-up process is free & will greatly speed up your computer. Takes about a half hour to run, +/-. (Afterward you can set this program to run automatically once a week or more, if you like.)