RailModeller

Shareware is a marketing method for software.

Software marketed through normal retail channels forces you to pay for the product before you've even seen it.
The shareware marketing method lets you try a program before you buy it. Since you've tried the program, you know whether it will meet your needs before you pay for it.

A shareware program is just like a program you find in major stores, catalogs, and other places where software is purchased - except you get to use it, on your own computer, before paying for it.

In the test version of a shareware program the functionality is limited in some ways. For example, RailModeller doesn't allow you to save or print layouts. Once you've paid the shareware fee you gain unlimited access to all program features and you are entitled to free updates for all future releases of RailModeller.