There is a concept introduced by other researchers that I use in my work, and IMO it is appropriate to rename it to honor the inventors. Is it considered normal to just go ahead and name it like that in my own paper? Should I ask the inventors for their permission? Are there any other considerations I should be aware of?
It is best to spend some time researching to ensure that you associate the correct person with the idea and mention related ideas by others. You wouldn't want a misnomer to be called a Squark - like Squark says: "Be LessWrong". :)
By simply explaining the concept and mentioning that you believe it was first developed by a particular person you permit others to write to you, the author, and correct you with earlier references, this comes across as better than expounding falsehoods and detracting from the creditability of your work.
When the person whom you propose to associate with the idea is available (alive, and replies to email) it is useful and respectful to contact them; they may be planning a retraction or know of another whom is actually the developer, they mearly refined (or copied) the idea.
The Wikipedia section on concepts has this to say:
Buildings, such as the Trump Tower, and companies, like the Ford Motor Company, are often named for their founders or owners. Biologic species and celestial bodies are frequently named for their discoverers. Alternatively, their discoverers may name them in honor of others. Occasionally, material goods, such as toys or garments, may be named for persons closely associated with them in the public mind. The teddy bear, for example, was named for President Theodore "Teddy" Roosevelt, because of a popular story in which the then-President objected to cruel treatment of a bear by hunters.
The fedora hat may be considered the "namesake" of a fictional character, Princess Fédora Romanoff, from an 1887 play, Fédora, by Victorien Sardou. In her famous portrayal of that character, Sarah Bernhardt wore a soft felt hat with a center crease, which became known popularly as a "fedora".