The appropriate duration of a Confidentiality Agreement will depend on your circumstances. There are two options for determining the length of a Confidentiality Agreement.
First, you can specify a date for the duty of confidentiality to end. Once that date has passed, the information in the Confidentiality Agreement could be freely used or shared by the recipient. If it is anticipated that the information will not be confidential after a certain date, it is appropriate to put a time limit on the obligations of confidentiality. For example, obligations might end after a product launch, after which details of the product would be in the public sphere.
In contrast, the duty of confidentiality can last indefinitely. In an employment situation, the employee’s obligations of confidentiality are likely to be perpetual because they may have access to their employer’s trade secrets, a category of confidential information which must always be kept confidential because they are key to a company’s profitability and edge over competitors. Therefore, an employee who agreed to keep a company's trade secret may be expected to keep that secret even after they have stopped working for the company.