I’m not sure what you mean by “impure thoughts that are no longer a problem.”
Many times we cannot help when an impure thought enters our mind. (Dwelling on an impure thought is another matter, though…that may be sinful and probably should be confessed.)
In any case, all of us–whether ordained, vowed, consecrated, or lay people who are none of those things–will have times of impure thoughts and times of occasions of sin. This will not cause a person to be excluded from pursuing a vocation, as we are not perfect…However, we are are to strive for continual conversion of heart and pursuit of holiness.
If there is an issue that is causing difficulty for you, speak to a priest. If you are considering the consecrated life, you should probably have a spiritual director so that you can discuss matters like this.
