Google maps gives you $200 worth of maps every month, at no charge. That is many, many thousands of map views. If your site gets more visits than that, they will charge you for it, but it would take a huge number of visitors.
You can also put a quota on your Google maps account. Tell it that you want to limit the account to $6.50 per day. That would be less than the $200 per month, so you would never be charged for any map use. If you get a huge number of visitors on one day, the map will stop working for the rest of that day.