1. You will receive all Professional Edition versions 2.x and 3.x including version 4.0 immediately after they are released.
2. If you buy a subscription for the Professional edition now then you obtain the right to buy with it also 200 shares at 50 cents per share (look at shares.html in our site). This means that for $349 USD ( $249 for the license and $100 for shares) you can obtain 200 shares and license for versions 1.x, 2.x professional editions and version 3.0.
3. You obtain technical support by e-mail and we will try to remove immediately all the problems in the compiler that hamper your work.
4. You will help for development of Strawberry Prolog. We admire any help. You can help with money by buying of shares or with ideas and bug reports. Also you can help by creating of powerful programs on Strawberry Prolog platform. You can take the source code of Strawberry Prolog and to make your own improvements on it.