While this is basically what Ian just said, here it is with more detail, if you will.
As far as Simbrief specifically, you must remember to unlock the current cycle while you are subscribed (nowadays, it’s usually a matter of accessing the Simbrief website while logged into a currently-subscribed account, although I have heard anecdotal reports of manual intervention being required).
Once a cycle is unlocked on Simbrief, it will remain available; you are free to switch between the cycle(s) you have unlocked and the free cycle (currently, that would be 2503 and 2608 if you unlock it; later on, 2603 and 2608, later on, 2703 and 2608, and so on)
That is, you have access to the current free cycle and whichever cycle(s) you unlocked while subscribed. Here what’s available to me based on when I was subscribed (vs not), for example, under my Simbrief account settings:
Note how I will keep access to cycle 2503 after it stops being the default cycle, because I was subscribed and unlocked said cycle when it was active.
Obviously if you subscribe for a month and cancel it, your list of unlocked cycles will be much shorter. That being said, if you were to e.g. subscribe today and cancel, you should retain one month of access, allowing you to unlock cycle 2608 now, and cycle 2609 starting on September 3, so long as you remember to do so before your subscription expires on or around September 13 (giving you an approximate 9/10-day window to unlock cycle 2609).
For navigation data that installs directly onto your hard drive, you can update only whilst your subscription is active. Once installed, the data will remain available indefinitely, albeit it may get deleted if you re-install your simulator or a specific addon; as I understand it, you are allowed to backup the navigation data, but doing so is your responsibility.
Navigraph’s FMS Data Manager (for X-Plane, Prepar3D, FSX) has a feature to backup the navdata packages to a central location whilst installing, and may be able to re-install the data from said backups (I never actually tried to use that feature). I don’t think Navigraph Hub has the same feature though. Some addons are now updated via e.g. an in-sim EFB, and I am not sure if or how the navdata update can be backed up in this case.
That turned out a little more comprehensive than I originally intended, but I guess that cannot hurt too much.
Let us know if you have further questions; and if someone spots something inaccurate in the above, please do let me know so I can correct it.
Regards,
Tim
