Can I create create a promotion based on customer's newsletter subscription?
Starting from extension version 2.17.0 we have introduced a new condition, 'Subscribed to Newsletter', enabling the configuration of rules based on the newsletter subscription status of registered customers. Please note that the functionality is available for Pro tariff of the module as a part of an active product subscription or support subscription. You can find the 'amasty/module-special-promo-conditions' package for installing in composer suggest.
To configure a discount rules based on newsletter subscription status, kindly navigate to Marketing > Cart Price Rules and for the rule required in the Conditions tab, kindly choose Subscribed to Newsletter:

Please note that this feature only works for registered customers.
Based on newsletter subscription status, If “Subscribed to Newsletter” is set to “Yes”, the discount applies only to registered customers who subscribe to the newsletter. If “Subscribed to Newsletter” is set to “No”, the discount applies only to registered customers who are not subscribed.

For the correct work of the feature, Magento Newsletter should be enabled in Stores > Configuration > Customers > Newsletter > Enabled > Yes:
Related Articles
How to create a promotion based on the Customer Attributes values?
To create a cart price rule based on the Customer Attributes conditions, you will need our Custom Promo Conditions or Special Promotions Pro extensions. The mentioned modules expand the condition options and allow selecting custom attributes created ...
Why is the Cart Price Rule discount not displayed on the Category pages?
Kindly note that this is expected behaviour for the discounts associated with a cart price rules not being displayed on Category pages. The point is that cart price rule discounts are calculated on Shopping Cart and Checkout pages, therefore, they ...
How to create flexible subscription plans?
Our Subscriptions & Recurring Payments has a ready set of sample subscription plans, however, you can always create new ones that might be more suitable for your needs. To create a new subscription plan, please go to Magento Admin Panel > Amasty ...
Can I apply catalog/cart price rules to subscriptions?
It is indeed possible to use cart and catalog price rules for subscriptions, however, there will be certain limitations. These rules will be applied to the first order only, i.e. the one that customers use to create a subscription, while further ...
The discount isn't working, what should I check?
This article contains the list of the major settings that can influence the work of cart price rules and discount application. It is recommended to look through it if you come across any difficulties with Special Promotions (Pro) discounts. If the ...