Hello Gioia Franchi 

Try the following steps: 

1. Close Studio.
2. Go to: C:\ProgramData\Trados\Trados Studio\Studio17\Data
3. Rename the file Studio.lic, e.g. to Studio_old.lic.
4. Go to: C:\ProgramData\SafeNet Sentinel\Sentinel RMS Development Kit
5. Rename System folder to System_old
6. reopen Studio and check if it works in Trial mode. 

Note: If you can't find the path above, open Windows File Explorer, click on View and check "Hidden Items" checkbox.

Thank you,

Sorin

Thank you so much! I tried the all path you mentioned but still it doesn't work and it asks me again the activation code!

Thank you so much! I tried the all path you mentioned but still it doesn't work and it asks me again the activation code!