No subscription fee involved. Each digital copy was obtained from a code inside the paper map’s cover. Has anyone else done this? I’m assuming that I have a perpetual license.
Yes. whenever you buy a paper map you can also download a digital version of it that sits in the OS App for you to use. Forever AFAIK.
The other option is you can pay an annual subscription and you can then view premium (1:25k and 1:50k) maps of the whole of the UK. You can also download areas to use offline without a network connection, which I assume are only accessible until your subscription expires.
The subscription is about £25 and for me is great value, you can also print off using their web service which is very handy to produce A4 maps of a walk etc.