Reporting felony convictions are required by law when applying for state licenses (CNA license is an example of a state license) and employment. The conviction may not necessarily prohibit you from obtaining the license, but in all reality, since CNAs are in the health care field, you'd probably find it pretty hard to find employment with a prior drug conviction. If you have successfully completed probation (i.e. no new arrests, paid all fines, completed any required drug programs, etc.) you may be eligible to file a motion to withdraw your plea or set aside the conviction, which, if available in your state, may afford you some relief. You'd have to find an attorney who knows how to do this and who can advise you accordingly.