Hello songyou;
Step 7 professional is a great package to have, even if it is an earlier version. Which version of Step 7 basis do you have, 5.2, 5.3? The only problem you will encounter would be if you need to program the newer CPUs and CPs, they will not be present in the HWConfig editor. But even themn, an upgrade license will be much cheaper if yopu want to go to the newer hardware.
With Step 7 pro, you have access to all 5 of IEC61131-3 laguages (as supported by Siemens, as some here will point out). So you have all the tools to learn and implement all the standard industrial controls used in the world today. And you have a good simulation software that will allow you to test and correct your programs without actually needing the hardware.
At the time it came out, Step 7 pro sold for about 3000$ CDN, aroung 2750$YS at the exchange rate applicable at the time. So yoes, idf all your icences are active, then you did not do too bad on the price.
Hope this helps,
Daniel Chartier