@021
In my experience, creating this add-on has required a significant amount of time and effort. Considering this, I suggest transitioning to a paid model for the add-on.
If you decide to go ahead with a pricing model, I recommend setting it at a lower price point. This would allow you to reach a wider audience and potentially increase sales, compared to a higher price that may deter some potential buyers.
Alternatively, you could offer a bundle deal by charging a higher price for all the add-ons you have developed, including future ones. This could provide more value to your customers and incentivize them to purchase from you in the long run.
In summary, these are just suggestions for improving your business strategy. Ultimately, the decision is up to you and what you believe will work best for your product and audience.