Handgun owners in Clark County must register concealable firearms at a law enforcement agency within an incorporated city of Clark County. The ordinance provides a period of at least 60 days of residency in the county before registration of such a firearm is required, and a period of at least 72 hours for the registration of a pistol by a resident of the county upon transfer of title to the pistol to the resident by purchase, gift or any other transfer.
The answer above is only based upon the limited information provided. The answer is limited and my review is likewise limited, and thus the response is not intended to be acted upon as legal advice. Although licensed in numerous states, I am currently only licensed to practice law in the state of Nevada. No attorney-client relationship is formed until you sign an attorney-client agreement with my office. Any information provided is for discussion purposes only and there is no attorney-client relationship formed. Only general legal information is provided. Each case is unique and accurate legal advice would require review of all details and documents for each specific case. It is possible that the comments here, while meant to be helpful, may in some cases not be complete.
Nev. Rev. Stat. Ann. § 202.360 specifies certain categories of persons who are prohibited from gun ownership. Primarily it prohibits ownership to those convicted of a felony or an "unlawful user of, or addicted to, any controlled substance." It is unclear if your prior activities were felony convictions, but if not, should not preclude ownership.
One way to determine if you are legally permitted to purchase is to attempt to purchase through a dealer, who utilizing the POS background check system will determine if you are permitted. A "delayed" or "denied" response does not necessarily mean you cannot purchase or posess a firearm, but a permitted will.