Follow these steps to purchase Premium:

1. Click on the Adblock Plus icon in your browser's toolbar. If you don't see the icon, be sure to pin it: How to hide/show icon.
2. On the ABP pop-up menu, click on Upgrade. 
3. Select the subscription option of your choice (monthly/yearly).
4. Click Checkout Now.
5. Enter your information and payment method.
6. Click Subscribe now.

Your extension will be automatically upgraded and you can immediately try out the Adblock Plus Premium features. When successfully upgraded, you will see a Premium emblem on the ABP pop-up menu. To redeem on additional browsers or profiles you use, please see the section "I've already purchased the Premium upgrade" below.

If you encounter an error after paying, please check out problems unlocking Premium. 

If you've paid for Adblock Plus Premium and want to redeem it in other browsers or had to reinstall ABP and removed your Premium upgrade, don't worry, you won't be required to pay again. 

Follow these steps to activate your upgrade:

1. Make sure Adblock Plus is installed: Check if Adblock Plus is installed.
2. Then go to http://adblockplus.org/restore-purchase.
3. Enter the email address associated with the purchase or contribution.
4. When you receive the emailed code, enter it in the field provided. If you don't receive the code, be sure to check your spam/junk folder. 

If you encounter an error, don't receive a code or experience another issue upgrading, check out problems unlocking Premium.