WooCommerce Subscriptions can send a range of emails for different subscription events, like renewal, cancellation or upgrade. However, it does not include any way to email subscribers before, or after, one of these events. Therefore, it does not include a way to email to a customer before her subscription renews.
The Follow-Up Emails extension on the other hand provides a great range of additional subscription related emails. It also provides tremendous flexibility in both the content and the schedule for these emails.
Follow-Up Emails can be used to email subscribers at a given interval before their next renewal is processed. For example, email subscribers 1 week before the next automatic subscription payment.