No. All Bannerflow contracts includes ad hosting.
All created banners are hosted and served by our fully-managed cloud ad hosting and is included in your contract. This is necessary in order to ensure that the banners are served correctly and remain available at all times as well as making it possible to update the banners without the need of having to republish the banners to websites or ad networks. Additionally, that we host everything for you is a huge time saver because HTML5 banners consist of dozens of files, that if created manually you would have to download and upload to an ad server.
All banners are "exported" by clicking on the publish buttons found either connected to each banner or on the larger Publish button at the top of each banner set. From there you can export the scripts that are loading the banners and send them to your ad network, or publish directly via an API integration.
We do not host external already-made banners although it's in most cases fully possible for anyone to easily recreate banners that are already made.