How do you define an active user?

I am struggling to define what an active user means for my product.

My product allows users to edit audio which involves three steps: importing a song, picking a result, and then exporting a file. Is an active user:

• anyone who visits the website?
• anyone who imports a song?
• anyone who plays a result?
• anyone who exports a file?

Since I am trying to monetize the product, I think the last definition makes the most sense since those are users who went through the entire process of using my app and are likely to convert to paid users.

But since I am targeting video editors, what if someone uses the website to find a good result, but then edits the song themselves? Should they count? They used the product, right?

In case you are interested trying the product to shorten, lengthen, or loop a song for your video, feel free to try it out here: https://mofi.loud.red/