One SDK allows one developer to develop an unlimited number of applications and distribute to an unlimited number of client desktops.
Please see Q10128 - HOWTO: License an EXE for Deployment for more details on proper license embedding.
Our imaging toolkits are runtime royalty free for client desktop applications. However for server installations, a server license is required.
Each developer who needs to compile a dll or exe referencing DotImage requires an SDK.
For additional licensing questions please visit our licensing page.