When you see someone introduced as a company's Chairman Emeritus, it means you're looking at a person who once worked as Chairman of that business. Now, that person is associated with the business, but mostly in an honorary fashion. The term Emeritus signifies the person still enjoys a similar rank to the position even though he's not doing the same work.
TL;DR (Too Long; Didn't Read)
A person can hold the title of Chairman Emeritus for life.
The organization only gives the Chairman Emeritus title to someone it still values as a member of the family. It means both parties are on good terms with one another. It is not uncommon for a Chairman Emeritus to continue to serve the organization in an advisory capacity.
Because it is mostly a ceremonial position, there is no extra pay for the title. However just like anyone else, a Chairman Emeritus can be paid for any work she performs.
The title is one of prestige that signifies past experiences and accomplishments. If the organization maintains a strong reputation, so will its Chairman Emeritus.