All violations stay on your record for 365 days (1 year) from the time they are issued. They drop off, after that.
If you’ve got a Level 3 violation, you’ll be able to use the Expert Server after seven days (one week) from the time that the violation was issued, since you’ll be downgraded to Grade 2 for that time. You can still use the Training and the Casual Servers though.
Just be careful, you have a combined level 2/3 violation total of 5. Your next one will keep you off the expert server until the oldest one reaches the one year mark.
While they don’t affect your grade or access to the Expert Server after one year, they will remain on your account/record and viewable by other pilots in the air. It’s something to be considered if that matters to you.