How to track "Support services" (as a product)?

How to track "Support services" (as a product)?

Hello Zohoers,
I am seeking for some guidance in my situation.

We are a software company and we charge additional cost for "Support Services" for our software product. My goal is to track status of "Support fee" that is paid annually.

Our customers are in different fee cycles (based on when we signed the contract) and we need to automate the fee collection tracking. So for instance, a date of pre-paid "Support Service" is approaching the end and we wish to be notified by Zoho that we need to contact the Customer. Moreover, we'd like to be able to do some Reports over this data.

I thought I can create a product "Support fee" however I cannot seem to find how to add flexible dates of start/end of the product (as the product is a pre-defined entity in "Products" module).

Any thoughts on how to achieve this?

Thanks!
Vladimir