https://www.pcgamer.com/world-of-warcraft-invites-lapsed-players-back-with-a-welcome-back-weekend/

You may have thought you were out, but World of Warcraft is ready to pull you back in with a Welcome Back Weekend. That's a catchy way of saying that lapsed players can jump back into the Azeroth action with full access and accounts upgraded to Warlords of Draenor or, if it's newer, your most recently-purchased expansion. 

The WoWWBW is good until June 24, and you can play as much as you want, to as high a level as you want. (The free World of Warcraft Starter Edition caps players at level 20—that's where to go if you're new to the game.) During that time, Blizzard is also offering 25 percent off a number of game services, including character transfers, and race, appearance, and faction changes.