How to display the renew button in Membership Plugin?

I've got one premium membership setup with finite membership. The customer has to pay by paypal without recurring payment. So I need a renew button for manual renewal.

My problem is that the even though I inserted [renewform] the renew button for paypal isn't showing up. I use PayPal Single Payments Gateway (by the way, the other one is called 'PayPal Payments Standard Gateway' and not 'PayPal Express Gateway' as it says in the manual).

The renewal period limit is set to 365 days, the upgrades period limit to 0 days.

Could you tell me the steps to display the renew button? Thank you in advance.