The 'disable' feature for memberships is an admin only facing feature.
A disabled membership:
is hidden from the public view
is hidden from and the front desk role
not discoverable in POS
not visible in the membership index page
can only be sold by an admin, and only from the subscription's details page.
Its ideal for a high level of control, where you don't want this subscription sold/given to just anyone. A good example would be a Staff Membership.
Its also helpful if you just want to temporarily power down a membership's sales from all areas.
Note: this is different from toggling off 'featured at checkout'. If a membership is featured at checkout, its discoverable by customers who are viewing your offerings online. If a membership is no longer featured at checkout it can still be sold by a front desk role through point of sale.
Admins can see a list of disabled subscriptions by navigating to Subscriptions and Packs > clicking Filters. To disable a membership, they can click the drop down menu to the right of it > Disable.
If the admin wants to sell a disabled subscription, they can click it > click new sale > add the customer and add the price (it will default to $0) > then take payment.
If the admin wants to re-enable the subscription so other roles can sell it. They can click the drop down to the right > then click Enable.