There is a way you can accept auto-recurring payments, just not involving our system in any way, as we have no way to initiate auto-recurring payments nor process orders for such payments.
If you choose to use PayPal Recurring Payments, using the Subscribe button codes provided by PayPal, that won't interfere with using the same PayPal account to take payment for your other E-junkie products. Any subscription/recurring payments you receive that way would be completely invisible to our system, so we would have no way of processing orders for those payments, nor tracking affiliate referrals/commissions, etc.
If you need to use our system, you would need to treat every single payment as a separate order that the buyer must place deliberately. You might set up a separate product for the continuing/renewal payments, or just provide buyers of the initial-payment item with a discount code they could enter when they place subsequent orders to make additional payments. This help page explains our discount settings: