The Subscription Upgrades module adds two additional options for products in the cart:

When enabled, customers will see an option to upgrade eligible products in their cart to a subscription.

This option lets customers select from available subscription options (if multiple are offered) and switch back to a one-time purchase if the Prevent Downgrades setting is disabled.

This is the text that shows on the upgrade button. By default, UpCart shows the Selling Plan Group Name on the button. You can change this anytime by removing the {{selling_plan_group_name}} variable from the button text.

This is the text that shows the subscription plan name and the {{selling_plan_name}}, which represents the frequency of your subscription intervals.

In order to change this text, you must check the box next to 'Allow Subscription Plan Options Text Override'.

This is the text that customers see when they choose to purchase a product without a subscription. By default, the text is 'One-time purchase.'

Similar to the {{selling_plan_name}}, in order to change this text, you must check the box next to 'Allow Subscription Plan Options Text Override'. The option to change it is below the 'Subscriptions Plan Options Text'.

You can prevent customers from downgrading to a one-time purchase by enabling a checkbox in the Subscription Upgrades module, located at the bottom of the settings:

By default, this option is unchecked. If a customer has a subscription item in their cart that also offers a one-time purchase option, a dropdown will appear, allowing them to select a different subscription plan or switch to a one-time purchase.

If this setting is enabled, the 'One-Time Purchase' option will be hidden from the dropdown, preventing customers from selecting it.