I can't find a reference to the website you refer to but it looks like you've been stung by what is sometimes called "scareware" which tell you that there is loads wrong with your machine and which it will put right if your buy the full version.
The truth is that there is most likely little wrong with your machine and if there is, there is no need to pay out to the scareware monger to get it fixed.
If you have any specific probelms with your computer you can post details here and the chances are someone will give you expert advice on how to fix it - for free!
Don't be misled into buying expensive and then useless software, even if it appears to be free when you first see it.
Always work on the "if it ain't broke, don't fix it" philosophy, like I do.
One bit of advice - never respond to unsolicited emails, especially if you don't recognise the company they are from.