Would be better to use it as a top dressing on your flower garden, but not near any of the solanum family. The compost will be 'spent' in other words the growing potatoes will have removed the nutriments.

Yes, just replenish the compost with fertiliser....i use chempak BTD plus nutrimate.

You might want to avoid growing Petunias, Callibrachoa, Salpiglossus, or Nicotiana in it, though.

Thanks to everyone who answered my question.
It cost me so much last year to grow about 15 potatoes,so I'm pleased that I can use it in some way this year.