Can you help me ?pleasei know this might sound dum me asking to some of you but?

i am using avg free verson i was sent a letter saying i needed to up grade to a nother one .be cause i all most used this one up .is this true or is some one just want me to use theirs. if this is true .who do i use next .and do i delete the other one first . i don,t know any thing a bout this .