How do I activate the program monthly?

Hello,
I’m not using Harmony very much right now. So I only want to activate it monthly.
How do I do that? I have two versions installed on my computer: Essential and Advanced.
Can I just enter a serial number or do I always have to download and install the program completely?

Thanks

If you chose a subscription, you can cancel it any time, otherwise you will continue to be charged every month. I think you can activate and deactivate the subscription as per your needs.