There was a time with Max Payne 3 when the Social Club stopped accepting many owners' serial numbers. Rockstar did some internal change to user accounts that invalidated a ton of keys. I emailed them and it took about a month to get going again. Real fast bunch of support folks there. Every Rockstar game on PC seems to end in frustration because of that Social Club bullshit. I tend to not like anything they make anyway so it's not a huge issue...