Date Formatting/Reading

Hi! =) I'm doing a website that will be using a pay-per-month membership program. There's a field for 'lastpaid' that holds the date the last paid (sorry to state the obvious). My questions are these: 1) What would be the best way to format it so PHP can see if it's been 30 days since it was last paid? 2) What line of code would be used to check? 3) Would I set the field type to DATE, DATETIME, TIMESTAMP or soemthing else? Any help you can give would be much appreciated! I woulda taken the time to study it more in-depth but I'm trying to get as much done on this in 5 hours as I can. =) ~ Tim -- From PHPGalaxy.com, earn up to $10 per order selling our PHP Scripts and Software on your Site. http://www.phpgalaxy.com/aff/ Also, get a fast free POP3 email account, you @php.la at http://www.phpgalaxy.com/search/