Update from monthly membership to lifetime membership

Hi guys!

I’ve a question: my users pays 9 $ / month for the membership. Some of them pay with Paypal, other with Stripe.

Now, can I use the upgrade form to change their membership from monthly to lifetime?
And, can I make only 1 form for this upgrade? Or I have to make 2 forms? (one for Stripe, one for Paypal?)
Thank you

You should make both forms (“modify” type), and by [s2m conditions] must show the need for to exactly user, to be possible such transition.

Alternatively, if you want to move all your members to one payment gateway, you must ask users to subscribe with new payment gateway, this can be done only manually by users, and then to unsubscribe them by old gateway.