Welcome to the community. 
The $59.99 USD option that you have been charged for is the yearly Pro subscription, which charged once per year.
The monthly Pro subscription is $7.99 USD a month.
If you were trying to purchase a monthly Pro subscription, you have chosen the wrong option.
Please feel free to send an email to support@wemod.com for further support. We cannot discuss payment issues too much in a public forum, because it involves personal information, which of course needs to be protected.