15 hours ago
15 hours ago - last edited 15 hours ago
As long as you buy a monthly membership plan at least every 6 months then your SIM will remain active..
Any time you don't have an active membership plan then you won't be able to use outgoing services (make calls, send texts, use mobile data) but will only be able to receive calls and texts.
If you mean that you want to always be able to make/receive calls and texts and use mobile data then you need to buy a monthly membership plan every month.
See here for more details - in particular sections 7.2 to 7.4:
If you need to contact 48 support about this then see the links in my signature below.