supporting member
A member of an organization who provides financial or other support, often without full voting rights or active participation. Common in associations, foundations, and non-profits.
This museum is operated with donations from supporting members.
正会員 is a full member with voting rights and active participation, while 賛助会員 is a supporting member who contributes financially but may not have full membership privileges.
Compound of 賛助 (support, assistance) and 会員 (member).