The Duration tab is where the royalty contract duration is specified.
Most book publisher agreements are valid for the duration of the copyright. In the United States this is the life of the author plus 70 years.
If the duration is for a shorter term select Agreement is for a fixed term. The duration can be specified by entering the duration; 5 year for example, or by entering the expiration date in the Expiration field.
In the Royalty contracts view you can add a column for the contract’s expiration date. To do this select the Settings icon (the blue gears). Then select the Columns… button and select the Expires field.
You can print a list of expired contracts from Reporting > Expiring royalty contracts.