Ted here from Shopify, thanks for posting your query!
Just to let you know, for any app that's installed using our App Store; if an app is removed from an account then this will reset the apps billing cycle, so you will lose any remaining trial days and will be charged for the app again if it's reinstalled. That being said, if you reach out to the app developers and ask them if it's possible to add the app again for free, they might be able to add offer some app credit so you won't be charged. App developers are not obliged to offer such credit or issue refunds but depending on the situation they might be OK with approving it as a one time gesture of goodwill.
If there is anything else I can help you with, please let me know, I'm happy to help!