YOLO
Life is to be enjoyed- Balance is the key

Life is for enjoying yourself. When you’re not in a dieting phase and you want to maintain your current results, or even improve further, does that mean you can’t have treats or go out and enjoy yourself anymore?
Absolutely not.
It just means you will have to work hard in the gym and be sensible with your diet. It may be beneficial to stay in a deficit of say, 300-400 calories per day for the week leading up to your night out to make room for the calories you will consume on that night. It may be worth roughly working out what you may consume on that night, then working out an average for this across the week.
It may be that you keep your calories the same but burn a few hundred calories more in the gym each day to accommodate the extra calories.
It’s all about energy balance and being sensible. If you were to eat at maintenance calories all week then go out every weekend, consume 4000 calories (Which is very easily done by the way), carry on like that week by week, how can you expect to see any major results? Why put all the hours in the gym if you aren’t going to see the results you deserve?
Think of energy balance as a bank account- If you were spending as much as you were earning, then every weekend you spent thousands, that wouldn’t end up in a great situation would it.
Being in a deficit of 400 calories is not a big deal for anyone. Why not sacrifice a few hundred calories per day for the sake of seeing a major difference in body composition rather than if you were eating at maintenance and gaining the pounds on a weekend.
Be honest with your calorie counting - If anything, overestimate calories. Even dieticians have been shown in studies to under-estimate calories, so overestimating may be a good idea to avoid this.
You only live once, go out and enjoy yourself! Just make sure that if you want to see awesome changes in your body, you accommodate this in the lead up!