PowerShell Universal is licensed per server. A server is defined as one running instance of PowerShell Universal. You can purchase a license for the entire platform (all features of Universal) or purchase a license for each individual feature of Universal (API, Automation and Dashboard).
Licenses for PowerShell Universal are perpetual and include one year of maintenance. After the first year, you can renew maintenance for 50% of the price of the original purchase. You will be emailed with a coupon to renew maintenance one month before maintenance expires. If you do not renew, you will need to purchase a new license at full price if you decide to upgrade at a later date.