Is the Subscriber Exchange free?
Yes. No money changes hands for a placement: the exchange runs on reciprocity, not payment. You host other members' ads in your channel and your own ad runs across theirs. Creating an account is free.
Do I have to host ads before I can run my own?
Yes. The exchange is host first: your own ad can run once at least one of your channels is hosting.
Can I control which ads appear in my channel?
Yes. You choose the kind of content you are willing to host, you can ask to approve each ad before it posts, and you can refuse any specific ad without a penalty.
How long does an ad stay in my channel?
A full day. Each ad is posted for you, stays up for that time and is then removed automatically, so there is nothing for you to take down.
Will other members know which channels ran my ad?
No. Advertisers see totals: placements, views and clicks, never which channels ran their ad. Hosts never learn who wrote an ad they carried. The one exception is a swap, a direct one-to-one promotion that both channels agree to.
How is this different from Paid Promotions and Cross-Promotion?
In Paid Promotions an advertiser pays for a placement in a channel they choose. In Cross-Promotion you pick a partner channel and swap posts with it. In the Subscriber Exchange nothing is paid and placement is automatic.