Discount gets applied without discount code.

I have added discount code with unlimited discount limitation.
I went through the whole process of purchase and the code worked fine.
Howeve, when I went back to purchase other items, discount got applied again without inputting the coupon code.
What should I do to make sure that user has to input the coupon code in order to get discount?

its a bit of a problem

it seems the discount code is automatically remembered by users computer

you can do a couple of things to get around this, you can set an expiry date on the discount voucher or you can set the discount voucher as 'one time per customer'

not a perfect solution i know

haydie,

Thank you for replying back.
However, that is not what I am looking for.
I need solution to either delete/expire session data in database when customer leaves the site.
Any ideas?