Is there a limit on how many times the form can be used and does it expire?

As long as the form is not purged, you can use it as many times and as long as you want. Purged forms are completely removed from our servers, however, deleted only forms can still be restored — How-to-Restore-Deleted-Forms

I hope this helps. If, in any case, I have misunderstood your concern, please do not hesitate to let us know and give us more details.