A Study to Assess the Safety and Efficacy of Risankizumab for Maintenance in Moderate to Severe Plaque Type Psoriasis ( LIMMITLESS )

* Participants with a history of moderate to severe chronic plaque psoriasis, who have completed one of the preceding studies. * Participants must be candidates for prolonged open label risankizumab treatment according to investigator judgment. * Females of childbearing potential must have a negative urine pregnancy test result at Baseline. If female, participant must be either postmenopausal, OR permanently surgically sterile OR for women of childbearing potential practicing at least one protocol specified method of birth control, starting at Baseline through at least 20 weeks after the last dose of study drug. \- Participants must have signed and dated a written informed consent in accordance with Good Clinical Practice (GCP) and local legislation prior to admission into the study.

* Premature discontinuation for any reason in the preceding study. * Participants who have developed guttate, erythrodermic, pustular or drug-induced psoriasis as diagnosed by the investigator during the preceding study. * Use of any prohibited medication or any drug considered likely to interfere with the safe conduct of the study, as assessed by the investigator. * Evidence of a current or previous disease, medical condition (including chronic alcohol or drug abuse) other than psoriasis, surgical procedure (i.e., organ transplant), medical examination finding (including vital signs and ECG), or laboratory value outside the reference range that in the opinion of the investigator is clinically significant and would make the study participant unreliable to adhere to the protocol or to complete the study, compromise the safety of the subject, or compromise the quality of the data. * Previous enrollment in this study. * Female subject who is pregnant, breastfeeding or is considering becoming pregnant during the study or within 20 weeks after the last dose of study drug. * Time elapsed is \> 8 weeks since the completion visit in the preceding study. * Participant is considered by the investigator for any reason, to be an unsuitable candidate for the study and not able to comply with the study protocol.