iNaturalist is a phone and web application that aids in identification, education, and community science. Here are a few things that I find worth noting about it's capability.
iNaturalist allows you to record your observations and organize them. When you upload an observation, the community can help confirm or comment on the identity. You can look at the observations from a map view, grid view, or list view. And there are all sorts of options for filtering and searching your observation list.
These lists can be made available to others to view and observations can be tied to various personal or community projects.
There is also a map view which can be help if you are looking for where the species has been observed locally or when traveling. Note, that when you upload your observation, you can hide the location or make it more generic. There is also an option to trust certain people with hidden coordinates.
There is great information on each species based on the observations found for that species, as well as other information pulled form Wikipedia.
The charts show when it is most common to observe the species as well as giving history on changes in observation numbers and life stages.
Plus some of the lastest pictures of observations. Which for animals, may also include tracks.
I find the "Similar Species" section especially helpful for birds and plants which to me are often hard to tell apart from one another.
This isn't about a subscription pricing, but about getting updates on a particular species, place, or community observer. I like Fishers (Pekania pennanti) so I subscribe to observations about them. I also like the IBM Glen Preserve, so I subscribe to observations found there. These can show up as an email or you can always see them on your iNaturalist "Dashboard". Be aware that if you subscribe to a very common thing (e.g. white-tailed deer), you'll see a lot. I believe this can only be set up and managed through the web application, not the phone application.
To subscribe to a taxon (species) or place, go to your "Dashboard" (click your avatar in upper right and select "Dashboard". The scroll down towards lower right and you'll see the "Subscriptions" section. Mine is already populated.
Here, you'll see two blue buttons that you can use to subscribe to either a Taxon or a Place. Clicking the "Taxon" button you'll be asked for what taxon. The field looks like a pull-down selection button, but just type in what you want to follow. If you type in a common name, you might have to scroll to find the exact taxon. Using the scientific name can help. See also the tip for species within a place below.
Subscribe to a place is similar, click the blue button and type in a place. There is a cool feature where you can ask for a place and then only a certain taxon within that place.
To check what your subscriptions are, click the gear-icon in the Subscriptions section and you'll be able to see, edit, and delete.
Perhaps you see someone who consistently uploads observations that interest you. Or maybe you and a friend just want to share what you're observing. Go to the person's profile and you'll see a little blue "Follow username" button. Click it and their observations will show up on your dasdboard.
You can also get notifications via email. To check these settings, click your avatar and then "Account Settings" and then "Notification".