Yes, payments are more than enough for the service that they offer. If there are legitimate trading mentors and you've been able to take all of their teachings then all up to you.
Can be additional payment, a token of appreciation like mugs, cap, etc.
Those simple things will be appreciated by them. Because a real mentor makes a lot of money from trading itself and they can buy everything unless they're just plain mentors that do not trade at all.
That's the truth because they don't need excessive appreciation when they have received payment according to the agreement. The most we can do is promote his trading to other people, that he really has good skills in teaching trading, so that many other people will learn from him. A reliable trading mentor will make money from many things related to trading and he will receive much more for his profits.
Promoting the trading services he has will be a form of respect for the knowledge he provides us. If we can do that, it will be much better and will have a big impact on the mentor. Everyone certainly has their own way of honoring the good deeds taught to us by others and touching on the development of their services in the best way may be much more important.
Mostly there will be a prior agreement and if the mentor is willing to teach voluntarily, I think there should also be appropriate compensation when in the future we have absorbed a lot of knowledge from him, and it all comes back to our conscience.
In fact, all knowledge cannot be measured with money, but there are other things we can do to repay kindness to the people who have taught us.
Currently there is almost no free trading knowledge that we can get for free and even if there is, it might be because they are close friends or it could also be because they are not reliable mentors in trading. If they are a reliable mentor, they will definitely not want to waste their time teaching other people for free. However, if we want to give appreciation for the knowledge they have provided, we need to see what they need because if we know their needs it will be easier to give them gifts.