Hi there @redzen!
Don here from Shopify.
Thanks for taking the time to outline your query for us here in the Shopify Community.
You can get support for this or any other third-party app from our app store by contacting the developers of that app using the contact details listed on the app store page.
From the info given there for this specific app, it appears that it is free to install this, and charges are then levied for the use of specific features of this app.
Based on what you have shared here I would take this to mean you will not be billed for the use of this app, but to be certain you would need to contact the app developers who would be the ones responsible for providing support for their creation.
Generally speaking, you would not continue to be charged for an app you have deleted from the Apps menu of your store, once the current billing cycle for that app has passed.
There's more info here on our help site on how app charges and app billing cycles work that you might find useful.
Would you still be setting your business up here and looking for ways to market your store?
What have you tried so far in terms of marketing or advertising?
Let me know if there's anything else we can help out with on the Shopify side of things here!