Cost per Registration (short: CPR) is a pricing model from the field of online advertising.
CPR refers to the total cost paid for an advertisement in relation to the success in generating new registrations. Basically, CPR is the ratio of the number of advertisement views and the number of successful registrations resulting from those ad views.
Therefore, cost per registration is a metric used to identify how much it actually costs a mobile advertiser to acquire new customer registrations.
To calculate the CPR metric, advertisers can simply take the total amount of advertising costs for a campaign. Then, they can divide the result by the number of registrations generated by that campaign.
You can find a detailed overview of all pricing models available in this article.