Some personal information is required when creating a subscription. In the Admin you can adjust which data is requested.
To do this, go to Settings → Subscriptions → Subscription Templates. Click 'Edit' for the subscription in question. Then select the 'Fields' tab. Please indicate here which information and items are requested and which of these are mandatory.
Make sure not to ask for too little personal data. For example, if there must be the possibility to contact the customer by e-mail, or if the identity must be checked at the entrance.