When you know the exact date that a subscription starts/ends, it's easy to provide the dates - but if you want to have a subscription start 7 days after the day it is purchased, or for it to end 2 months after it's started, that requires a little bit of extra work - that's where this library can help.

Paste the following code just before the closing </head> section of your page template.

<script type="text/javascript">
// moment.js
// version : 1.7.2
// author : Tim Wood
// license : MIT
// momentjs.com
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</script>
<script type="text/javascript">
	jQuery(document).ready(function() {
		var re = /^((?:\d+[d|m|y](?=\ |$)\ ?)+)$/;
		var tier_re = /^(\d+)([d|m|y])$/;
		jQuery("input[name='sub_startdate']").each(function() {
			if (re.test(this.value)) {
				var parts = re.exec(this.value)[1].split(' ');
				var start_date = moment();
				for (i in parts) {
					if (tier_re.test(parts[i])) {
						var tier_parts = tier_re.exec(parts[i]);
						if (tier_parts[2] == "m") {
							tier_parts[2] = tier_parts[2].toUpperCase();
						}
						start_date.add(tier_parts[2], parseInt(tier_parts[1]));
					}
				}
				jQuery(this).val(start_date.format("YYYYMMDD"));
			}
		});
 
		jQuery("input[name='sub_enddate']").each(function() {
			// Set it to today
			var start_date = moment();
			if (jQuery(this).parents("form").find("input[name='sub_startdate']").length == 1) {
				var start_date_input = jQuery(this).parents("form").find("input[name='sub_startdate']").val();
				if (start_date_input != "") {
					if (start_date_input.length == 8) {
						// It's YYYYMMDD
						start_date = moment(start_date_input, "YYYYMMDD");
					} else {
						// Assume it's DD or D
						start_date_input = parseInt(start_date_input, 10); // Remove the leading 0
						if (moment().date() > start_date_input) {
							// Day already passed, move to next month
							start_date = moment().add('M', 1).date(start_date_input);
						} else {
							start_date = moment().date(start_date_input);
						}
					}
				}
			} else {
			}
			if (re.test(this.value)) {
				var parts = re.exec(this.value)[1].split(' ');
				var end_date = start_date;
				for (i in parts) {
					if (tier_re.test(parts[i])) {
						var tier_parts = tier_re.exec(parts[i]);
						if (tier_parts[2] == "m") {
							tier_parts[2] = tier_parts[2].toUpperCase();
						}
						end_date.add(tier_parts[2], parseInt(tier_parts[1]));
					}
				}
				jQuery(this).val(end_date.format("YYYYMMDD"));
			}
		});
	});
</script>

This script requires that you're using an add to cart form, so you might have something like this inside your form:

<input type="hidden" name="name" value="subscription" />
<input type="hidden" name="price" value="20" />
<input type="hidden" name="sub_frequency" value="3m" />
<input type="hidden" name="sub_startdate" value="2m 5d />

This script makes use of the moment.js library - and allows you to specify a value for the sub start and end date using it's time setup - so if you want the subscription to start 1 year, 2 months and 3 days from the current date, you'd set up your sub_startdate with a value of “1y 2m 3d”.

Monthly subscription with one month free access

<input type="hidden" name="sub_frequency" value="1m" />
<input type="hidden" name="sub_startdate" value="1m" />

Subscription product to represent a monthly repayments set up of 3 payments

<input type="hidden" name="sub_frequency" value="1m" />
<input type="hidden" name="sub_startdate" value="01" />
<input type="hidden" name="sub_enddate" value="2m 1d" />

Note that for the start date, providing the date as DD or D will cause it to start on that day of the month, which if it's past will be the following month. We set the end date to 2 months from the start date, as the start date is technically the first payment, so 2 renewals later will be the third payment.

For the subscription end date, it will be based off of the start date if you specify one. So if today is the 1st of January, and you set the start date to “1m” and the end date to “4m”, that will mean that the subscription will start on the 1st of February, and finish on the 1st of June.

• http://forum.foxycart.com/discussion/6264/subscriptions-how-to-limit-the-renewals