Why Move from WordPress.com to a self-hosted version?
Functionality. That is the main reason, people want to be able to do more with their website but shouldn’t have to spend $300+ on getting the features that they need.
Need Before You Start
To start with the move, you’ll first need a domain and a hosting plan. If you already have a domain with WordPress.com you can refer to there guide on updating your nameservers to point to another host.
Step 1: Exporting Your Blog Data
Make sure that you are already signed into your WordPress.com account. Go to your blog’s dashboard. On the left-hand column, you will need to click on the WP Admin link to open your blog’s admin area.

In the admin area click on Tools » Export.

Clicking on the Export tool will take you to a new page where you can select to export your content and/or media library.

You will be sent a download link once your export was successful.
Step 2: Importing Content into your new WordPress Site
You will head to the exact same spots as in step one but instead of selecting Tools » Export you will need to go to Admin »Tools » Import.
You will need to install the WordPress importer if it not already installed and then select the downloaded files from step 1 and then import your data.
Tips:
Make sure to redirect any blog links from your old site to your new site
Move Subscribers / Stats
Install Jetpack so you can keep the blog subscription function