I’m not qualified to say whether using software without paying is halachically asur but it certainly displays bad midot and it would create a chilul HaShem if frum Jews became known as software pirates. This is considered by the software industry to be theft, pure and simple. If everyone used software without paying, the entire industry would collapse, there would be no new software created, and thousands of people would be out of jobs. I personally know frum Jews whose parnassah would be ruined! If you can’t afford an expensive program there is a good chance there is an inexpensive or even free alternative. For example, there is a free office productivity suite that has most of the capability of Microsoft Office and reads most MS Office file formats that can be downloaded from openoffice.org.