49 Pa. Code § 21.725
An LDN may request that his license be placed on inactive status. The licensee will not be required to remit the biennial renewal fee during the period when the license is on inactive status. In order to return to active status, the licensee shall submit proof of completion of a minimum of 30 hours of approved CPE in the biennial period preceding the request for reactivation and pay applicable fees. A person who requests an active status license who has been on inactive status for 5 consecutive years shall satisfy the requirements of section 6(b)(4) of the act (63 P.S. § 216(b)(4)), unless the person demonstrates that he has an active license to practice in another state or has had an RD registration or a CNS certification for at least 2 out of the last 5 years.
49 Pa. Code § 21.725