If you have any problems, then firstly try to read FAQ and Support forum of free version, because most of troubles are the same.
If you used a free version, and then installed a paid one. Then you need to re-create all the cafes and delete the old ones!
Check if you have right specified the shortcode. You must indicate your cafe’s id in the premium version (example: table-reservation cafe_id=”268″ ).
Also try to update the cache.