With zombies run, there are different options.
With the free mode you can unlock a mission a week and replay it, though since one mission is 20 minutes or so, this probably won't work too well if you want to do at least a mission a day as I do.
However, then there are various other options, from buying a season pass to unlock all missions of a given season (about 25 in all), to subscribing, which you can do for £5 month or £30 a year, (I'm afraid I'm not sure what that is in South African rand).
Actually, whilst I'm not usually a fan of subscriptions either,in the case of zombies run I'd suggest an exception. Firstly, the subscription gets you everything! all the missions (now over 500 I think), all the side quests, any new stuff they do, and they bring out new stuff almost every month, indeed if it weren't for the subscription they'd be pretty expensive buying different things individually, not to mention that the subscription also gives you access to a few nifty little bonuses like a faster item collection rate, and membership to their website which gets fun stuff like emails to you from people you save on missions. It even gives you access to their other aps, the walk and zombies run 5 k training, which I haven't investigated as yet, though might do if I ever run out of missions .
second, is the quality of the audio itself. The recording and acting is extremely good, as are the characters and the story over all. Considering that each mission comes with between 5 and 10 minutes of audio and each season is about 25 missions, that's still a pretty good price considering that people like big finish and graphic audio will charge you twenty quid for a stand alone two hour audio drama.
I'll say for me, zombies run works out really well. Previously, I could only stand doing about a 12 minute run, since otherwise I'd just plane get board, and need to do something else. but with zombies run, needing to run to actually finish the mission, I find myself hanging on just to end the story, and heck, some of those missions have been pretty epic.
For example, in Venus rising (one of their none zombie adventures), I actually did! get to do the big dam hero thing and run away from an exploding fuel tank across a collapsing bridge in a space colony that was falling to bits. Now, tell me how any exercise can be as straight up awesome as that .
But, as you can start off for free, and do the intro, why not just give it a try. I bought the subscription literally two days in once I realised that this was going to be fun, and whilst annoyingly I had to stop at christmas due to me getting ill, then due to my lady going in for radio therapy, I'm now definitely getting back to things and I'd certainly say I've had my money's worth .
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)