Your PMP certification can be revoked in the following cases:
- They discover after bestowing the PMP status upon you that you have cheated in your PMP exam.
- They discover (also after granting you the PMP) that you have lied in your application (for exampled, lied in the number of experience hours). In this case they will audit your first, and if you fail the audit, then they will revoke the PMP. This type of audit is called a post PMP audit.
- You have lied in your PDU reporting to maintain your PMP application (for example, you have stated that you have gathered the necessary 60 PDUs while you only gathered 30). Again, before revoking your PMP status, they will audit your PDU reporting. Note that I haven't heard of a single instance of someone getting his PMP revoked because of this.
- You have failed to pay your PMP renewal fees - in this case they're not really revoking the PMP status, but it's you who doesn't want it anymore.
While I always think that honesty is the best policy, in this case it might get you in real trouble. If you tell them then they will most likely revoke your PMP and ban you from taking the PMP exam. It's up to you to decide...