The question is, can a complaint against my professional license be made anonymously? The answer to that is yes. Most boards and state agencies accept anonymous complaints at some point during the process, up to and including a hearing. However, the person making the complaint will not remain anonymous initially. If someone accuses you, and the investigators require information from the person who made the complaint (the anonymous individual), and you decide to exercise your right to a hearing, assuming it gets that far, they will have to locate that person and have them testify. The person may also need to produce documentation, testifying to the authenticity of those documents to enter them into the court record.
So, initially, yes, a complaint can be made anonymously. However, in the course of a contested hearing, considering the rules of professional conduct and rules of evidence, that person would not remain fully anonymous or anonymous at all, as they would have to testify and potentially produce documentation to support their claims. I hope this clarifies the process.