The car documents you must keep valid
To drive without worry, four things must always be valid: the RCA, the technical inspection (ITP), the road tax (rovinieta) for national roads and the registration certificate. The registration papers and license are asked at any check.
The road tax is checked and bought online through eRovinieta, and the validity of the RCA and ITP can be found in the official apps. A tip: note the expiry dates in your phone, with an alarm a week ahead.