A subscription based on CERTGATE service template (SSL certificate subscription) does not have "Edit" button in the provider's control panel:
Home> Operation Director> Support Manager> Subscriptions> Subscription #ID
The issue has been confirmed as incorrect product behaviour, internal issue ID is #PBA-52873.
The bug is fixed in PBA 6.0. As a temporary workaround, it is possible to change the subscription settings (e.g. related to autorenewal) from the customer control panel.