I am planning to create 1091 photos into one file that shows mapping and elevation difference.

Thanks for reply,

If I try to upload all 1091 photos, only a maximum of 444 photos can be uploaded.
That's why I asked if I needed to subscribe to be able to upload more than 444 photos.

Additionally, I have two goals.

First, create a photo of 1091 photos (.jpg extension) into one file.
Second, create contour lines in CAD.

I use a contour software called 'Quikgrid' that allows me to create contours using latitude, longitude and altitude (METIC) information. 
So far, I have only extracted and used latitude, longitude, and altitude information using kml.extension files, but if there is a better way, I would appreciate it if you could suggest it.

The maximum number of images that can be uploaded to the system goes up as you process more maps. To start, the maximum is the greater of 600 or 300 images per map you have run. For example, to run a 1000 image map you would need to have at least 4 maps processed first.

You can see this in Step 4 of the upload where is says the following:

"Maximum goes up 300 images for each map that gets processed up to the maximum of 4000."

We encourage you to run increasingly complex jobs to learn your way around the system but you would technically be able to continue with your intended dataset as long as you have the required number of maps in the system. They can be free/small if needed.

Also, you may need to purchase points to process 1091 images. You only get a certain amount for free. The uploader should tell you how many points you need when you select the imagery. 

A DEM elevation file is created when you process your images into a single orthorectified image. The DEM is a TIF file. Run the sample data or a smaller subset of the imagery through the system so you can see exactly what you get. 

I don't think I understood the answer well, so I'm asking one more time.

If I was planning to combine 1091 photos, a maximum of 444 photos could be attached in one mapping operation.

444+444+203.
After a total of 3 small mapping operations, how do you combine the 3 small maps?

For Zane's example, 300+300+300+191. (4 times)

How do you first perform a total of 4 small maps, and then combine those 4 small maps?

I don't understand that part.

"We encourage you to run increasingly complex jobs to learn your way around the system but you would technically be able to continue with your intended dataset as long as you have the required number of maps in the system. They can be free/small if needed."
Could you explain the above explanation in a simpler and more intuitive way?

I don't see an account for you in the system so I can't see what tier your account is currently on. There is no limit of 444 images. You can run 1091 images but you might have to run a few smaller jobs first or pay for the additional processing. It sounds like you are just trying to use the Free tier and combine things. 

You can use our Location Map feature to combine the web maps. 

https://support.dronesmadeeasy.com/hc/en-us/articles/207455313-Creating-a-Location-Map

Or you can combine the GeoTiff files on your own: 

https://support.dronesmadeeasy.com/hc/en-us/articles/115003641246-QGIS-Raster-Merging

My subscription tier is for 'free' now, and I am planning to subscribe to do this mapping project.

I can work on 1091 photos by dividing them, but the main goal is to know how to do them all at once.

I am working on my own using Raster Merging in QGIS.

However, I would like to process 1091 photos in just one process. I'm even willing to pay for all cost(sub + purchasing points).

Which subscription tier should I purchase and how should I calculate the cost?

With the Free tier you get 1 gigapixel worth of processing for free. You can purchase points to process additional imagery all in one shot at a rate of 200 points per gigapixel. 

As noted in your screenshot, the maximum number of images that can be uploaded at one time goes up by 300 with every job you process so you should run some sample data through the system to become more familiar with it. This means that after uploading 4 smaller maps your maximum number of images will go up 1200 images. Do this and then you will get a more accurate point total for your full dataset. 

Thank you very much for your detailed and quick answers to all my questions. 

I will try one more time. :)