Since it is an entirely prepaid service, PM does not allow the temporary suspension of a current subscription the way you describe. Once a plan is paid for, it runs continuously until it expires. You can keep an inactive/expired account and phone number for a maximum of 89 consecutive days after the expiration of your current plan. If not reactivated, the 90th day after expiry results in account removal and loss of phone number. This 89 day countdown resets after any activation and subsequent expiration, even if it's just an activation of a 10-day plan.
It sounds like you are on a 90-day plan. If you are gone for 6 months, there are these options:
1) If your plan is a grandfathered or promo plan, then you'll have to renew it at least once during that 6 months, within 89 days after expiry, in order to keep the plan. You will not be able to change to a cheaper plan without losing the promo/grandfathered plan forever. An unused 90-day subscription is the price you'll pay for keeping that plan.
2) Same as above, except you find someone to temporarily take over that 90-day subscription that would otherwise go to waste.
3) If your plan is not a grandfathered or promo plan, you could let your plan expire by removing autopay before your payment due date, then wait up to 89 days before activating a cheap 10-day text only plan for $11. When that expires, then you'll have another 89 days to reactivate on whichever currently available plan you want. Note: For both activations here, you'll need the help of a moderator by private message, as only they can change plans on an expired account.
If either your plan or your phone number are important to keep, I would recommend not waiting the full 89 days before reactivating, just in case there are unforeseen problems, so you'll have a safety margin.
