One time purchase is a single purchase made by a customer.
It allows the customer to buy the item once.
One time purchase gives the customer the option to purchase an item not as a subscription.
A one time purchase option can be displayed alongside subscription plans on the product page.
When creating a subscription plan group, you’ll have the choice to add “One time purchase” as an option.
You can limit your subscription products to being sold only as a subscription or enable both subscription and one-time purchases.
In Ongoing App:
This feature is currently only available on the Ongoing app extension that appears under the Subscriptions sections of your Shopify product page. See below for details.
On Shopify Admin:
From Shopify admin, click Products
2. Click the product you want to manage the subscription of
3. Select whether to sell the product as a subscription only:
To sell the subscription as a subscription only, check Only allow purchase of this product as a subscription
To sell the product as one-time purchases as well as subscriptions, uncheck Only allow purchase of this product as a subscription