There's also a way you can get this programs for free. Through bulletin board services that offer free sharewares. First you'll need a modem, which lets you connect your computer to the phone line. The best sources for these programs would be America On-Line. A shareware program is meant to be a trial program.
Registration is outlined in the program itself, or the documentation that comes on the disk.
For registering, you will usually get a package of items from the author than can only be gotten by registering. This usually includes a copy of the latest version of the program, sometimes with extra features, and a printed instruction manual. Items might include free or low cost updates to the program when available, phone support from the author, or other programs the author has written. It really is worth it to register the program. After all, you've gotten the opportunity to inexpensively try the program to make sure it will fill your needs.