As many times as you can place it naturally. Do not place keywords forcefully. The normal ratio could be 1 time in the title, 1 time at the beginning of the description, and one time at the middle or end of the description. Also, you can place the keyword in the tag section once as well. In the description part and tag section, you can also place related keywords if necessary.
However, the excessive use of keywords should not spoil the beauty of natural writing. The reader (your buyer) needs to be impressed after reading your gig description. So, try to make the description convincing and reader-friendly.