@Adi ****
Some people here say that as soon as you have the visa, there are no existing requirements anymore.
But when you ask embassy or immigration office in Thailand they will tell you that the requirements are for each entry, which also makes sense, because you got the visa for a specified purpose.
When course is finished you don't have a valid reason to enter Thailand.
Why should you be admitted and someone else who wants to enter on visa exempt not?
On the other hand for most people entering the country there will be no checks, but there is always a small chance you get checked.
You can gamble that you not get stopped, but keep in mind that it might be, and also in the future they might check more often, like they do for ED visa.