What is the best practice for age verification landing page in CI?

[eluser]term25[/eluser]
Thanks, for your solution. In the end I ended up with using the database table for this task, becaouse it turned out that I need to store also the IP and date when the yes button was clicked on the verify page and the actual address where the user want to go (e.g. he want to go to something.com/product/2356 this address is saved too. so I saved his address no matter what in the db every time he enters every page, then there is a check script if the date is less than 24 hours, if not he is redirected to the verify page and if he click on yes, the date is rewritten in the database and his IP has another 24hours . He do not have to be registered to enter my page so this is the only way I know of that can achieve something like I wanted.