Zoiper Biz Desktop license is one time fee, no monthly or annual taxes apply. Also it is licensed per seat and OS. You have the option to reset a license up to three times in case of PC/device malfunction or OS change, after that you would need additional license.

Updates are provided for free for the same point release (e.g. from zoiper 1.49 to zoiper 1.50). 

Upgrades to a newer version (e.g. from Zoiper 1.x to 2.x) or changes between operating systems or different versions of Zoiper might require additional payment.

Please note that no voice termination services or origination services are included in this license fee.