01) Access the Control Panel
02) After login click on Catalog
03) Create a Category Subscriptions
04) After creating a new product
You will have the Recurring Payment field
Select YES
Fill in the period and frequency
05) After clicking the button to Add / Update the product
06) You need to configure the PayPal Payment Module in the Control Panel >> Modules >> Payment >> PayPal
Note: Automatically will be charged monthly subscription through PayPal