How safe am I doing this?

If you use it, you are pirating the software, and (unless you live somewhere that does not recognize copyright law) can be prosecuted for theft for the retail value of the script, plus possible additional fines and damages.

If the value of the script (or other pirated scripts that get found if you get busted) go above a certain value (varies from jurisdiction to jurisdiction), most places will consider it a greater crime, and prison is not out of the question.

With that out of the way, there are a few things to know when you "preview" a script:

Don't leave any readme.txt or .nfo files in the folders on your server that contain information about cracked or nulled software. This is one of the major ways that people get busted.

If you do get busted, have a story ready to go about outsourcing to a contractor on the Internet, and "make things right" by licensing the software immediately, or taking the site offline. Most script providers just want to get paid, or failing that not have you profiting off of them, and most times, this will be the end of it.

If you make decent money off of the site, then pay the fees to license the software properly! First of all, it is the "right" thing to do, and secondly, it protects you. The worst thing that you can do, IMO, is to make serious money off of the script, and not pay for it. This will piss all sorts of people off, and they will simply want your head on a platter if they catch you.

Best of luck.

nothing will happen.

you see bhw peeps doing it everyday, lol.

Do a search for letter or warning, and you will see that plenty of bhw people have been given legal notices for using unlicensed scripts.

Thank you mattstrike. One more question: How can they know I am using their script?

Didn't Harro get one a while ago? Didn't seem to bother him too much

Many scripts will have a specific file (like an xml or css file) that has a very specific name, or sits in a very specific folder structure, and often, just a simple search with such a highly specific string will turn up a list of indexed sites running that software.

I do this all the time, in fact, to find Joomla sites, so that I can see what other people are doing with it (like an eye on the competition, so to speak).

If you take a look at a "real" version of a script, and a warez version, though, you will often find that the warez version has one or two additional files, such as a ReadMe or an NFO that take credit for the cracking/distribution and possibly give some install instructions.

When a script writer discovers that someone is pirating their script, they will go out to the warez sites, and track it down, and see what files are in there, and then do a similar search, for sites that are running their scripts and where someone forgot (or simply did not know) to remove these files, and copied them up to the server along with the real files.

Make sure you leave no traces behind (like mattstrike said)
[check it's properly nulled, delete everything that could blow your cover].
An additional way of being secure would be to host the whole thing on some offshore server!
(But that would cost you pretty much, depending on the provider )

Thanks to everybody fot your replies