I know that if I use tor my isp can see it. Can this cause me any problems. Could it for example pretend some explanations or contact me about this issue? Thank you for you precious help.
As a Tor user you're very unlikely to face any repercussions from your ISP, as long as you don't contribute to Tor by running a relay. Using Tor is not illegal in virtually all jurisdictions. Unfortunately, we don't know what will happen in the future and it is possible that someone records that you're using Tor today to use it against you tomorrow. The best defense is to get as many people as possible using Tor so that it becomes an even more normal thing to do.