The number of active campaigns you can create depends on your subscription plan.
On Delivr, one campaign = one QR code and Short URL
A QR code is just one embodiment of the Destination URL defined for a Campaign; others are, for example, NFC tag and Short URL link.
An active campaign is typically a campaign visible through your Account Dashboard. A paused campaign is still considered active. A campaign must be archived to became inactive, in which case it will not count towards your plan's limit. However, if you restore/reactivate the campaign, it will once again count towards the limit.