slightly 'iffy' tekkie question

[Tanky]

Hey all. Need some tekkie help (again) and i'm not sure who else to ask as the fella that recommended i try this has naffed off on holiday.
Unfortunately, i suspect what i'm trying to do may be 'a bit naughty' so apologies if i'm a little vague.

I've downloaded a 30day trial of a piece of software, and 'apparently' you can also download keys which allow you to turn trial versions into full versions. I think i've managed to get one, but i need to know, am i likely to damage anything on my pc, how can i be sure its the right one and how i get this key thing to work?
Alternatively, is it likely that the same file sharer will have the full version of the software in question and is that likely to be damaging/ dodgy as well?

any help or ideas (that don't involve actually buying expensive stuff!) appreciated
cheers!

[Banners]

You can download keys which allow you to turn trial versions into full versions by going to the website and putting in your credit card details.

M@