Hi NikoKino if you are just using Sheetgo to transfer the data from one spreadsheet to another your workflow won’t be affected and you can keep using the free account. But if you’re also using the Transfer Formatting, this is a feature that is only available for paid users, in this case when your trial ends you won’t be able to use this feature anymore.
We do have a workaround which is the parse data feature, you can read about it in this article, but for it to work properly you would need to be sure that both source and destination are formatted the same way.