Drupal needs someone to write a payment module for subscription -- 2

Drupal needs someone to write a payment module for subscription. Currently, I want customers to have a 7-day free trial and then automatically pay the amount when the 7 days expire. I am currently using the default setting, where it allows a 7-day trial without requiring PayPal registration. After the 7 days, it prompts customers to enter PayPal, which is inconvenient for me. I want customers to still register with PayPal during the 7-day trial, but after the free period, it should automatically renew. Can you handle this, and how long would it take to complete?