The renewal mechanism of .it domains follows this pattern:

• domain is active ("ok") until the expiration date
• the day the domain expires, it enters in "autorenew mode"
• at this point if the Registrant has already renewed it, the domain remains in autorenew mode for 15 days, after which it will return to "ok" mode and the expiration date postponed for one year (and only then the expiration date on whois will be updated)
• otherwise,  if the Registrant has not already renewed, the domain will be placed in "pending delete / redemption period"

A .it domain which is not renewed in time, and therefore is in "pending delete / redemption period" mode, can still be recovered by the Registrant. But redemption is expensive, and during redemption time the domain does not resolve (so, your web site, nor your email service works). So, it's very important to renew an .it domain before his expiration.