Right license(s) for a freemium offer

Question

I am currently working on a solution written in JavaScript. I plan to release two versions:

• For free: the lite one with base options, which is plug and play (it just works when loaded in the page)
• For a subscription fee: the full version that has more options and requires support

I am wondering which license(s) would work for me. Here are my thoughts so far, feel free to correct me:

• MIT: I am concerned that somebody else might release new features on top of my solution, under a commercial license. It means that I wouldn't be able to add these same features to my own solution in the future.
• GPL: doesn't seem to work in my case, if I release the lite version under GPL then it means that I also need to release the full version for free.
• Dual licensing: I see that some frameworks or libraries offer dual licensing, but I am not sure how it works.