Which Gulf licence do I need: DHA, DOH, MOHAP or SCFHS?

The licence depends on the country and on the emirate or region where you will work. Ask the employer in writing which authority licenses the post, then confirm the requirements on that authority's own website. DHA, DOH and MOHAP are UAE authorities, and SCFHS is the Saudi authority, so the work location your employer states decides which one applies. Our clinical nursing practice includes questions styled for all four, and the UAE destination page lists the exams that apply. Use the practice as preparation only, because the questions are not official exam material. Do not pay a recruiter for a licence decision, because the authority issues the licence and no agent can decide it for you. Keep copies of your certificates and your application receipts, and check the official fee list before you make any payment.