You don't provide much information, but I'll make some assumptions and see if the answer helps. The type of crime you were convicted of may be important. If it was a drug case long ago, the Real Estate Commission might not care much. If it was embezzlement of trust funds, they'll care a lot. By "expungement", I assume you mean that you got relief under Calif. Penal Code Section 1203.4.
This type of "expungement" will not help you much in this situation. You still have to disclose the conviction when applying for your license. That does not mean that they have to refuse to issue the license however. It just means you have to tell them of it. If you were applying for a job working for Intel, you could legally deny it with a 1203.4 order having been issued, but the state occupational license is a situation in which you still have to disclose.