https://www.guildwars2.com/en/news/guesting-is-coming/
The wait is over! Guesting is coming to a world near you with our update on January 28th!
Before I go into more detail about how it will work and what kinds of restrictions exist, I want to talk about a very important change that will come with the introduction of guesting: free world transfers will no longer be available. With the current restriction of one transfer every 7 days in place, make sure that you will be on the world you intend to play on before January 28th, because after that date, you’ll have to pay a gem fee to transfer worlds.