14 CFR § 65.15

Except for repairman certificates issued in accordance with § 65.101, a certificate or rating issued under this part is effective until it is surrendered, suspended, or revoked.

Unless it is sooner surrendered, suspended, or revoked, a repairman certificate issued in accordance with § 65.101 is effective until the holder is relieved from the duties for which the holder was employed and certificated.

The holder of a certificate issued under this part that is suspended, revoked, or no longer effective shall return it to the Administrator.

Except for temporary certificates issued under § 65.13, the holder of a paper certificate issued under this part may not exercise the privileges of that certificate.