PortSip SDK's

All packages license are Unlimited end-users. Buyer pay one-time license fee in return for the rights to distribute his application to as many end-users as he like without paying any royalties or license fees to PortSIP.
The purchased SDK license cannot be transferred to any third party. The purchased SDK license can only be used by the company who purchased it to build products. All packages include one year free updates and technical support.

The license is lifetime validity, but if you want to receive the new versions and technical support after one year, you have to renew your license.