G'Day
As rojash said, trial versions are try before you buy or stop using it. So if you like it then buy it.
Yes it can be bypassed. There are all sorts of methods used by software writers to determine whether you have already had the trial period - things like entries (1 or more) in innocuous locations in the Registry, hidden files on your disk (sometimes in hidden folders), files that are named as something that is seemingly nothing to do with the program (these files do nothing - they just exist as a marker). So if you want to bypass it, you are going to have to try and determine what method, or combination of methods, has been used and then go through every file and registry entry and remove the ones put there by the program. This is dangerous because if you remove the wrong item your system may lockup completely or refuse to boot at all which means reinstall time.
Of course you could do a clean install of everything and get a new trial period - but wouldn't it be easier to just buy the software - it is obvious you want it.
Geoff