How hard is it to remove the adhesive from tile if needed?

I haven't tried to remove it from inside my tub. I need it there permanently! It is very strong. Just what I was looking for!

Description says it has to be reinstalled after a month "because this is a vacuum." What does that entail? Every month? Extra adhesive? needed?

No, this is a vacuum suction cup, no glue is needed, just remove it（Push the transparent lowering button to the right position.）, and then reinstall it . Installation steps： 1, Ensure the surface is flat,smooth and dry.Clear the smooth surface 2, After the wall is dry, press the suction cup firmly on the wall,push out the air. 3, Continuing to hold in position, Push the transparent button to the left position.You must slide down to the end. When you hear a "click", the lock will be completed. 4, The others non-smooth surface please use 3M adhesive disc first(provided in package)to overcome them.such as rough wood,emulsioni paint,textured tile, etc.

How do I get the suction cups to stick to a regular wall? The instructions say the surface must be dry but the suction doesn't hold.

The others non-smooth surface please use 3M adhesive disc first(provided in package)to overcome them, such as rough wood,emulsioni paint,textured tile, etc. Or you can try to reinstall：Push the transparent lowering button to the locked position.Note: You must slide down to the end. When you hear a "click", the lock will be completed. Please contact me if you have any questions