Hello!
I work right now with the free version of TD but I was commissioned for a paying project which is a fixed installation.
My question is what type of licence do I need?
I assume the pro one -but my main question is do this licence is good only for one computer ( in other term only the installation ) or could I eventually use it for other paying project?
Thanks!
Antoine
The Commercial license is totally sufficient if you do not need specific features only enabled in the Pro version.
A license is only valid on one computer at a time. So, in theory you could build your project and leave the license on the fixed installation computer, but you would need to buy a new one for the next commercial project.
A good way here is to buy a designer license for yourself and renew it every year and simply buy commercial TouchPlayer licenses for the deplyoment.
Thanks a lot for the infos! 
I cannot find the info on how much does a commercial TouchPlayer license cost.
Do you happen to know where I can find this info?
Thanks again!
Right here, on this page, not hard to find.