Your channel must meet the YouTube Partner Program threshold and your videos must meet these minimum requirements in order to be monetized:

• Your content is advertiser-friendly.
• You created the content or have permission to use it commercially.
• You are able to provide documentation proving you own commercial rights to all audio and video content.
• Your content complies with YouTube Partner Program policies, YouTube’s Terms of Service, and Community Guidelines. YouTube reserves the right to disable monetization for accounts that do not follow our guidelines.

Examples of content that may be eligible for monetization

• You filmed your cat and there is no background music.
• Your video contains royalty-free music, and you can prove commercial use rights using a direct link to its terms.
• Your friend created content for your video and states in writing that you may use and make money from it.
• You created original music yourself and are not signed to a label.

Examples of content that would NOT be eligible for monetization

• Your video has music you purchased on iTunes or content you taped off of television.
• You edit together a compilation of content created by others.
• Content with violence and/or nudity meant to shock and disgust.

You can review additional tips about content your videos might contain here. 

* Nguồn: Youtube