Can you apply for residency if you have a felony of sales of a controlled substance?

Your question requires an attorney consultation. It is not a simple question that can be answered on this type of forum. There are many factors that would need to be considered and evaluated. Most drug convictions will make you inadmissible and/or removable. I strongly suggest that you contact an experienced immigration/ attorney for a face-to-face consultation and give him/her all of the facts surrounding your situation. He/she would then be in a better position to analyze your case and advise you of your options.