Subscription form with limitid users and option to remove yourself

Hi,

I'm looking for a form solution for event subscriptions. There should be an option to ad a number for maximum perticipents.

Is there a SharePoint online integration?

Thanks for the feedback.

I'm looking for a form solution for event subscriptions. 

You can check out these form templates: https://www.jotform.com/form-templates/event-registration 

There should be an option to add a number for maximum participants.

You can add the limit to the whole form: How-to-Limit-Submissions-in-a-Form OR, do it based on the options or sessions from your form, you can use the following widgets:

http://widgets.jotform.com/widget/quantity_gift_registry

http://widgets.jotform.com/widget/appointment_slots

http://widgets.jotform.com/widget/inventory

http://widgets.jotform.com/widget/ticket_purchases

You can add any of these widgets to your form by following this guide: How-to-Add-a-Widget-to-your-Form 

Also a user should be able to subscribe for someone else.

You can integration a payment processor into your form and add a recurring payment option via the Sell Subscription option. Please check this guide for more details: How-to-Setup-a-Recurring-Payment-Option.

If the form link with this integration is shared with another user, they can subscribe on behalf o someone else. 

Also a user should be able to unsubscribe for the event.

Here is how the subscription can be cancelled if the recurring payment option is integrated into the form.

1. Authorize.Net - Subscription must be canceled by you from the Authorize.Net account dashboard.

2. Stripe - Subscription must be canceled by you from the Stripe account dashboard - How-to-work-Square-Subscription-and-Cancellation 

3. PayPal - Users allowed to cancel their subscriptions from within their PayPal accounts. You can also cancel the subscriptions from your PayPal account dashboard.

Is there a SharePoint online integration?

Here please check this guide to integrate with Sharepoint: Adding-a-form-to-SharePoint