how to convert pptm to keynote?

A pptm file is a Powerpoint file with embedded macros. Very doubtful if Keynote can open or save these files as Keynote does not have the ability to use macros.

PowerPoint or Open Office can open and play these files and you could save as a ppt file. This will remove the macro but will prevent the macro running and may cause the presentation not to work as desired.