Limit Number of Trial Membership/Credit Packs Sold

When creating membership/credit pack trial, add an option to limit the number of times a user can purchase it.

If the member tries to buy the membership more times than they're allowed, show an error message explaining why they can't buy it.

If the staff member tries to sell the membership to someone who's already bought it the maximum amount of times, warn them but let them still sell the membership if they want to (e.g. if the member had bought the trial before but not used it, and now the staff want them to have another opportunity).