> ## Documentation Index
> Fetch the complete documentation index at: https://docs.plude.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Changes

Simple subscriptions rearely change. One created, they often hold a single `subscriptionItem` and bill till their termination date. Advanced subscriptions on the other hand, may change often. Changes include *quantity*, new *add-ons*, *up- and downgrades* and change in products.

Regardless of simple or advanced, Plude is enabled to assist in every change.

## Applying Changes

### Adding a new item

```bash theme={null}
curl -X PUT \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer {your_token_here}" \
    -H "X-environment: {your_environment_id_here}" \
    -H "X-version: 2022-03" \
    -d '{
        "Start": "2023-01-01"
        , "End": "2023-04-30"
        , "AutoRenewal" : true    
        , "Items" : [ 
            {
                "id": "fdca8173-f7ec-4ce8-6ea0-08dca8fd442a",
                "billAt": "2023-01-01T00:00:00",
                "quantity": 2.0000,
                "productId": "fdca8173-f7ec-4ce8-6ea0-08dca8fd442a",
                "priceId": "fdca8173-f7ec-4ce8-6ea0-08dca8fd442a",
                "prorate" : {
                    "strategy" : "remaining_period"
                    , "prorationDate" : "2023-02-01"
                }
            }
        ]
    }'
    https://api.plude.io/subscriptions/{d6b18512-8c4c-4c41-86e9-8cda6335232a}
```

# Proration

## Applying price and product

In the next chapter you will lean how both price and product align with subscription items for effective billing.