All legal
The licenses would be a good idea, but won't always ensure 'responsible' ppl, there are plenty of shit drivers out there with licenses, and its not exactly hard to drive a car without a license, albeit illegaly, can still be done as long as you don't get caught. With drugs all you will have to do is use the substance and thats it, you won't get prosecuted at all, so,if anything all the illegal users will have more substances if they were legalized but only to licensed users. People will do what they want anyway, some people just won't take heroin, and will prefer the effects of certain drugs, there are plenty of ppl who have used an entire catelogue of drugs, but ended up being an alcoholic. Some people will naturally inhibit there use to stay away from the long term negative effects, others like we see in modern day society, won't. Like the alcoholics we see on the streets, but many hold down business jobs, same with other drug addictions, had a few teachers who were alcoholics. Everyone expects it to turn in to armageddon, smackheads roaming the streets, stealing for there next fix, needles everywhere, but why would they be stealing? and why would they shoot in the street? if the stuff was legal, and didn't interfere with gettin a job, then the smackhead roaming the streets would be of the same mind as the average mugger, stealin cuz he's a prick, not cuz he has no other means of gettin money, and he'd shoot at home mostly, as what I've heard from heroin it just makes you completely content with everything, most choosing to lie down and let it ride over them. There's crime now, there's drugs now, and its illegal, if there was no law this shit would still be happening, but the need for crime would decrease because it wouldn't be as beneficial, because it would be available everywhere, and there's ALWAYS going to be drugs, every civilization in the world has a drug, and we seek recreation, people know heroin is out there, and pills and the like are easy as shit to get, and people do tek em, but most, use it on weekends, or monthly, occasionally more, I don't think it would particularly change very much.