Plugins Menu is Missing on WordPress Dashboard

Hi there! My blogs are hosted in wordpress.com and I want to customize them by adding some plugins. As usually if we want to add plugins, we go to Plugins menu which located between Appearance and Users menu. But now i can’t find Plugins menu, it’s not exist. Could u tell me why this happened ?

I’ve google this problem and still not found the answer, please help me!

I’ve assumed that maybe this happened cause i using free wordpress? CMIIW

Thanks for attention!