INCOSE SEPs are allowed to use the logo for their certification - ASEP, CSEP, or ESEP - while they are actively certified. They may use this logo on business cards, in their email signature, or in other ways that recognize them as a certified individual. The INCOSE SEP logos may not be used in advertising a business. Training provider companies that prepare individuals for the INCOSE knowledge exam may not use the SEP logo in their advertising or training materials, except for things like a screenshot of the INCOSE website or listing the credentials of individual employees. Organizational use of the SEP logos requires INCOSE pre-approval, and has been granted for things like custom mugs given to new SEPs.
Here is the INCOSE SEP logo policy, CRT-100