HELP ME! I can’t figure out “Shopify” (I know that there is a textbook on it, but it is not entirely clear to me), could you please record a video tutorial on it, for example, you can how to disable ads in a $ 1 game using Shopify, please, I really need it!
Shopify isn’t a GDevelop system. GDevelop just has some options to use it. You can read about those options here: Shopify [GDevelop wiki]
You would need to investigate with Shopify resources on its proper setup and usage for the shopify side.
However, shopify isn’t a microtransaction system, it is an ecommerce store for products. As far as I’m aware you’re not going to be able to do the type of transaction you’re looking to complete.
Also, please do not demand people make video tutorials for you. This is not a GDevelop specific recommendation, but a general internet one. 
Ok, I won’t anymore 
And I didn’t demand, I just asked
I noticed that your post is from a couple of years ago, so you’ve probably sorted out your Shopify issues by now. But just in case you—or anyone else stumbling upon this old thread—are still having difficulties, I’d like to offer some help.
I understand that Shopify can seem complicated if you’re new to the platform. While I can’t record a video tutorial at the moment, there are tons of resources available online to guide you through whatever you’re trying to achieve, from setting up a shop to managing ads.
For comprehensive assistance tailored to ecommerce solutions, you might want to check out transformagency.com. They offer a range of services that can help you get the most out of platforms like Shopify.