Your subscription will renew the same day of the month when you were first charged for the first time at the end of your free trial.
For example, if you subscribed on July 1, you will be charged on July 8, then you will be billed on August 8, September 8, and so on.
If your regular billing date is on the 31st of the month, but the next month has fewer than 31 days, you will be billed on the final day of the month.