There can be long term effects after you abuse a drug. Often included is a likely permanent negative transformation of the way you react to the drug. Why would pot be any different?
From my personal experience I have known social anxiety, depression, fiending (strong psychological addiction), withdrawals (appetite suppression, irritability, and insomnia), and physical panic to be the most common long term effects. However I was bonging over an ounce a week, plus hash, plus oil dabs, so even compared to most daily smokers that's simply not comparable. Long term effects or the all-too-common 'uncomfortable highs' are just possibilities to be aware of, nothing definite. Thinking ahead to potential outcomes and adjusting your behaviour accordingly to avoid risk is a wise course of action. The higher the frequency that you smoke, or use any drug, the greater the chance of encountering noticeable long term effects. Also note the 'long term' part of long term effects - I smoked weed habitually for years before it started messing with my body and mind. The safest way to ensure that you'll be able to enjoy weed into your elder years is to use it at a frequency that upon reflection you feel is not overuse or abuse. I'd personally say once a week max but your mileage may vary of course. It could be a puff at the end of each day, but in my opinion that is even pushing it, because unless it's for medical purposes daily drug use is generally discouraged from the point of view of harm reduction.
I abused weed, smoking weed was like all I lived for over a period of years. Blatant abuse; smoking bong rip after bong rip, or usually volcano or dabbing - not just smoking enough to stay high, but compulsively abusing weed because I had turned into a fiend since I was chasing constant, strong euphoria from it. This eventually transformed me into a total burnout. I haven't smoked it in two years, and I'll never be able to smoke it again, because the side effects became extreme and I could never use something again which has resulted in so much harm to myself. It was a complex, multi-faceted and valuable life lesson, and luckily it was with 'just weed' or I might not be here writing this, but with drug abuse also comes regret. The regret does not come from how I can't smoke weed anymore and I used to enjoy it a lot. It's a much deeper form of regret than that. It taught me, among many other things, how to respect drugs. I purely use psychedelics now, once every couple weeks, Mdma twice a year, and I have used pain medications for my severe chronic back pain for years without getting addicted (from my vantage-point on the topic of addiction) or taking more than prescribed or than I feel comfortable using, which I attribute to the lessons I learned from abusing weed. Otherwise I'd probably have ended up chasing some opiate high, taking more than I require to manage my crippling back pain, which I simply have no interest in. But getting addicted to weed shed a lot of light on the phenomenon of addiction as a whole (not just to drugs, but habitual tendencies in general, such as how some people are 'addicted' to watching porn frequently.)
I think the ideal way of using cannabis is to space your highs out and not make it a regular thing, unless you have a medical reason to use it (which most people who smoke weed do not). Although that's just my opinion, because in the early days smoking weed was a truly magical experience easily on par with one of my favourite psychedelics like high dose LSD or mushrooms. Obviously not as intense, but I used to get really freaking blazed and it was incredibly fun. Then with overuse it turned into complete garbage, all positive effects were lost, but nevertheless it took me so long to break my deep seeded attachment to it, and to come to terms with the fact that weed wasn't what it used to be and that it didn't have a place in my life anymore. In order to accomplish this, and break my attachment to the herb, my ego had to take the back seat since I had to acknowledge that I had made a lot of mistakes (among other things, like how I simply couldn't tolerate weed anymore and I used to smoke like a chimney). Another issue was that I had allowed cannabis to become a part of my personality, the image that I projected onto other beings. The withdrawals were truly miserable as well with a complex array of symptoms with the post-acute phase lasting at least 6 months, both 'physical' and 'mental' (in my ideology, I don't differentiate between the two), with the more 'physical' side effects like appetite suppression lasting a solid month. Essentially I required weed in my system during that in order to be able to normally consume food (I puked more times in that month than I have throughout the rest of my life).