Well, first off, if your primary concern is conversions you initially need to do two things:
1.) Have a professional look.
2.) Carry this look consistently across all pages.
You`re good with #2, but your main header logo is not professional looking, to be honest. When a site involves money in any way, the smallest factors can be a turning point between their decision to buy or not. So i would redo the main logo, i would also recommend avoiding the use of the type of gradient you`re using for the header image too.
Next, i`m assuming by conversions you`re referring to software sales (after all, a conversion, is anything you designate it to be)? If so, then you`re structure is setup all wrong. If people are lookiing to checkout your products, they will go to the products section and read about that specific product, and if they`re interested they will either download or buy it... but here is where you`re missing some key things. If they`re reading a description of that product, right under the description you should offer two links, one to download the trial, the other is buy. And you should do this for every product. Because if they have to search for these links (which are under "downloads" and "register software") you`re going to lose quite a few conversions. Effectively you should have a method of allowing a customer to download or buy from any page of a given product.
As for selling, i would alter your "copy", aka your wording, a bit. For example, i`d avoid using the words like "spy software" and instead emphasize "privacy" more and so on. I`d actually almost recommend changing the name. As a programmer i follow its name easily, but rarely are your customers going to know what a computer session is...etc. Instead you should pick a name that instantly speaks to a non-tech user, its purpose. Even further explain what a keylogger is to the uninitiated. They may be tech products but even a tech savy ceo may not follow all of your description.
Well, i hope that helps.
Edit: You also have some 404`s, like
Edit2: After reading further i see your english wording is also a bit choppy. If your main market is english speaking buyers, then correct english will also help you quite a bit.