How to set Product Subscription Expiry Date or intervals

[osamafarooqi71]

Hi, I want to allow users to select how long s/he wants to receive the subscription product like 1 week, 2 weeks, 6 weeks, or 12 weeks. The shipping intervel is something else which is handled using the selling_plan. I want to set the expiry date. I'm currently using this code 

 item =    {

                quantity: 1,

                id: 89080322787,  //variant Id

          selling_plan:  9089323789, //selling plan Id

                properties: {

              expire_after_specific_number_of_charges: 2  //number of charges

                }

              }

and then submit this data using Ajax Cart.  Is this correct?

Anyone, please share that how I can achieve this?