Hello, I just bought the pro version of wemod and I don’t like it, wemod deducted about 70$ from me and refunded it immediately. I wonder if after 3 free days will any additional money be deducted because for me $70 is quite a lot.
Hello and welcome to the community. 
As with all subscriptions provided by all subscription services, such as Amazon Prime, Netflix, Playstation Network, Xbox Live, and so on - including WeMod - you will be charged to continue the subscription if you do not cancel it before the free trial ends. It is just how subscriptions always have worked - even in the past before the internet existed (ie, magazine/mail order subscriptions).
This is clear on the Pro subscription page, as well as the Terms of Use that you agreed to before registering your account.