You can indeed use Paypal subscribe. The option only appears if your invoice is not yet due.

Log into your billing account at https://service.iitsp.com , click on your invoice and the option will appear at the top right of your screen.

It will not appear if your invoice is overdue.

It is therefore best to use this function when you receive notification that an invoice has been generated.

Note:
This option is only available to clients being billed from our https://service.iitsp.com system. This includes Host On A Rope, Penzai Hosting, AllWorldIT (UK) and Linux Based Systems Design, Ltd.