The amount of time that an employee stays with an employer depends on various factors, and of course works both ways.

Example:

An employee remains with the only till he or she is confident and satisfied with their growth and an employer wishes the employee to stay with them as long as they are sure that the employer is productive and profitable.

The only answer, therefore, to this question is that you are looking for a long and productive career with the company. You would also have to reiterate that you have chosen to work with the company for various reasons such as reputation, quality that the company represents in the market as well as the future that the company aims toward.