Some do. Check when you sign up. For non-free plans, none of the providers we recommended limit the amount of data you can use. Some will limit how many devices you can use at once -- although, for paid plans, VPN providers tend to offer more connections than you will need. As a general rule of thumb, free or trial offerings tend to restrict usage, speed, and/or the number of devices you can connect to the VPN, with access and speed increased for paying customers.