Are you German?
No no, although I learn it, and sometimes it overwrites my non-native English, too.
You would need to check the liscencing for Construct, but most game creation tools allow you to sell the games you make with them commercially. And as long as you can make it and sell it, the tool is only a means to an end. The tool itself isn't as important as your skill at using it. From what I can tell from Construct, it has all the features necessary to make a decent indie game, even one that is sold commercially.
A more pressing question would be what sales platform you are shooting for. This will dramatically affect your ability to sell the game you construct. If you intend to release the game on the PC, you need to look into possible sales systems. Maybe you want to integrate it with Steam, in which case you will need to pitch Valve on your title. Maybe you want to use your own sales system, or perhaps go through PayPal. All of these factors can affect your choice of game creation system / engines.
As for Construct's license, it allows commercial production. But its being so young makes me uncertain if it can create worthy games.
Thanx for selling tips, yes, this will be another great topic, but first I should find the suitable tool for development. Happy that GameMaker,and things that you mentioned have already proved their worthiness. Anyway, heard so many good tidings about Construct, maybe it is also worthy to developers' attention? I am at novice-intermediate level with it, and hope to achieve my aim.