SIRIUS XM radio in my used car i just got, how to renew it?

i just bought my 2008 caliber and it came with SIRIUS XM, the car was a rental car b4 and maybe those guys had renewed it but now i got it and its july, how would i renew it when it goes out and how much would it be? im a 20yr old guy and having this radio is so tight! they dealer ship never told me it had it, i didnt know till 3 days later, thanks ! oh and its a regular stock radio the kind know one sells just what the manufacture puts in lol.