One's criminal history is available, and increases the penalties for new charges, until one has stayed out of trouble long enough to apply for a Pardon.
I would think enough time went by on the IA charge to apply for a Pardon, but the drug charge sounds more recent. He should probably have at least ten years without charges to put him in a favorable position to ask for a Pardon.
There is more information about Pardons at the website link below.
A criminal record never goes away. Once a person has been convicted of a crime, that person should expect that if he or she is charged with a new crime the prosecutor and the judge are going to consider the previous conviction. And when they consider the previous conviction, the best they'll likely do is only hold it against the defendant a little bit. A prior conviction certainly won't make a judge or prosecutor view a defendant more favorably. The theory is that each time a person is convicted of one crime and then committs another crime, it becomes more likely that even more crimes will follow.
Most likely forever, a person's criminal history is part of them, much like their arms and their legs. Of course, there are situations when someone may be eligible to expunge part of their record, but that's not usually the case.