Shareware is a way to distribute software. It gives you the chance to try it before buying it. If you continue using shareware program beyond its free evaluation period (1 map and 4 routes to measure in case of MyWay), you must register it.
Copyright laws apply to both shareware and retail software. The copyright holder retains all rights, with a few exceptions. The author of shareware usually specifically grants the right to copy and distribute the software.
There are good and bad shareware programs as well as there are good and bad retail software programs. However, the advantages of shareware programs are their ultimate money back guarantee retail packages just cannot offer. There is also much better selection of shareware than retail titles, and so you might be able to find the package which will fit your needs more accurately. And most importantly, shareware programs are offered for much less than their competing retail distributed equivalents largely because of the lower overhead and no advertising budgets on shareware side.
In short, if you like the program, register it and if you have a chance, please pass the original unregistered version on to a friend. If you do not like the program or if it simply does not meet your expectations, we thank you for trying it out and would like to ask you to tell us what should we improve or fix.