Some tips for this question:
• It is not right to be specific; else you are giving them the impression that you are not going to stay if hired.
• Specifics here are not good. Something like this should work: I’d like it to be a long time. Or As long as we both feel I’m doing a good job.
Sample answers
• I’d like it to be here a long time; as much as you permit me and believe that I am doing a good job to remain in your company.
• I worked for my previous employer … years. That demonstrates my loyalty. So, as long as the work is challenging, and I will have growth and training potential, I will be happy to work here.
• First of all I pity you for hiring me, I will rob you blind, eat all the almonds and pee in the punch bowl any chance I get. So the answer to your question is, until you catch on.