Date code required to add to my current perl script

I have a perl cgi script in operation that is basically a redirect script which when a user clicks a link on my page it takes them to another site. I charge a small fee to the companies that I list their link on my pages. What I need is to add the ability for an email to be sent to me by this script when I have had that company on my site for a given period of time (say 1 year). Getting my script to send the email is not the problem. The problem is I need to have the script calculate the date and send me an email when a link has been on my pages say for not quite a year, then this would give me time to send them a bill and advise them their link is about to expire. I have a date setup in the script so as it saves to a flat file dbase, this date is the date the link was activated on my page. As I said all I need is to work out how to calculate the date for a future date so as I can have the script send me an email when that future date arrives. I realise a cron job may be needed here, but I was thinking since this script is run each time a user clicks on one of these links it could check the dbase and see if any email needs to be sent to me. ## Deliverables Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. Complete copyrights to all work purchased. ## Platform Unix, Perl 5