noun
A fee paid to register something, such as a membership, a domain name, or a legal document.
会員になるには登録料が必要です。
A registration fee is required to become a member.
ドメインの登録料は毎年支払います。
The domain registration fee is paid annually.
参加費 is a participation fee for an event or activity, not necessarily involving registration.
Compound of 登録 (registration) + 料 (fee).