The short answer is no, they stay the same unless you ask us to change them or elect to do any of the following options that would require us to provide you with different IP's.
We use Amazon Elastic IPs for our service and they are permanently reserved.
If one of our services associated with an IP fails, we have an auto-start service that will use the same IP instantly. Since all of your inbound/outbound requests process via our load balancers, this underlying restart and change would be transparent to you and your endpoint users.
If Amazon ever changes its Elastic IP policy for some reason, we will obviously inform you well ahead of time. We've never seen this happen, but leave it open here as a remote possibility.
Possible Reasons A User Would Require An IP Address Change
There are a few ways the IP addresses could change, based on decisions made by a customer, so we wanted to point them out in case this is something you might do in the future.
One way the IP's would change is if you decide to change your proxy to a different region. Then those IP's are going to be different as they are on a different proxy region.
For example, if you decide to switch from US-WEST to EU-WEST, then those IP's would be different from your prior region.
Dedicated Proxy Setup
Enterprise subscriptions (and above) are eligible to move their solution to their own dedicated proxy resources. This allows for more stability, security, and customization, and all usual things that come from moving off a shared resource to a dedicated proxy.
If you believe you might want a dedicated resource for your solution in the future, then it would be best to make that change early, so you don't have to inform downstream vendors or suppliers that your IP addresses needed to be changed.
Change from QuotaGuard Static to QuotaGuard Shield (or vice versa)
The reserved IP pools for our Static and Shield proxies are different and can't be used together. If you change from one product to the other, your IP's will have to change as well.
Potential Solution to Changing Products
You can always have a QG Static subscription for your development/staging servers and a QG Shield subscription for your production instance. Many of our customers implement this solution, so that their production IP's don't change, but they can also have a different set of IP's to develop and test against that customers and other downstream vendors don't have to know about for their connections.