Ensure the plan is active and check the customer's account settings to verify that they are assigned to the correct plan.

-Check if Under orders you have updated the order status , if the order status is still processing it will show processing to the customer. 

-If the order status is still Cancelled the payment entry will not be visible to the customer 

Or 

-If the customer has enrolled into the plan using their email address and later next time they using their contact number then in such case plan entry will not be visible to the customer.