selected>join vetices (I have this on the space bar) - joins two or more verts at the mean distance between them.
If you need them at a precise coords then selected>align verttices
or
object>join closed vertices - and set a distance tolerance

I have all these on a keyboard shortcut due to their usage

File>configuration>keyboard and you can set keys for any function and sub function. (I think this is available in the freeware?)