Unlocking is a process that frees your phone from being locked to one specific carrier. It increases the retail value of your phone and lets you switch carriers easily.
Once you purchase the unlocking service and send us the IMEI of your phone, there's nothing left to do. We'll do all the work to get your phone unlocked by your service provider, and we'll notify you when we've finished.
No. It's completely legal. On February 11, 2015, President Obama passed a law that allowed unlocking services. Read more here.