Best database design practices recurring payments

I have a question regarding the 4 extra columns needed or recurring payments to work properly. Since I am using a dynamic MySQL database for my products, I am assuming that the best way to pass these 4 variables to the shopping cart is to have them added into 4 unique database fields. The 4 fields that I was thinking of adding are:

ProductRecTerms
ProductRecAmount
ProductRecFrequecy
ProductRecAmount

Would this be best practice when it comes to where this information is stored in the database?

Let me explain what I need to do. The website I am designing will be selling live insects as food for lizards and other small exotic animals. The website will offer these live food items in a subscription and non-subscription format. Ideally I would like to give my customers the option of being able to upgrade ANY item for sale as a subscription sale. My next question is, would I need to create a copy of every item in my products table, for example, 500 Crickets non-subscription in parallel with 500 Crickets subscription? Or can the subscription upgrade be handled with a separate database table, let's say a table called "Subscriptions" that in turn would store these 4 unique cart variables used to make the subscriptions work? Or would the addition of such a "Subscriptions" table be over complicating things? Any guidance in this area would be greatly appreciated.

Additionally, I would need to be able to sell both recurring payments and non-recurring payments. From what I have seen posted in other forum comments, it does not seem possible to do this without some kind of heroic programing to make is possible to accept both kinds of payments.

The cart will handle this automatically. It will do recurring payments for items that have Terms defined and single payments for those that don't even if they are in the same cart.

Thank you Ray! That was just the critical piece of information that I needed to hear. Now I can start building out this project. I'll be sure to update you of my progress and ask for your help when I get stuck (I will get stuck at one point or another).