Plugins are saved in the %amosplugins% folder. Amos "knows" the folder location and saves plugins there by default.
In Amos 23, plugins were saved in a subdirectory of the Amos program directory. Many Amos users are not allowed to create files in that directory. On the other hand, all users can create files in their %amosplugins% folder. In addition, locating plugins in the %amosplugins% folder allows each user on a multi-user machine to have their own plugins directory.
Amos 23 plugins require updating for Amos 28.