For digital downloads, you pre-pay for a certain number of downloads up-front before you distribute and you're covered up to that number. We suggest you license what you think you will sell in one year. It's up to you to monitor your actual sales and make sure you do not exceed what you have licensed. If necessary, you can come back to us and get a new license for additional units. If it's an exact re-order without changes, our fee is half-price. This makes it easy for you to license only what you need upfront and avoid paying too much in fees for reorders. Better yet, if you have purchased the Seal of Authenticity with fee-free reorders, you will avoid our fee entirely and pay only the additional royalties owed.
For Custom Licensing, the quantity, along with the term (duration) and regions where you will distribute, is important and will affect the fee proposed by the copyright holder. For custom license requests, you should estimate quantities for digital releases in the same way as you would for your cover songs.