Hi Eujuanv,
Welcome to the Apple (user-to-user) Community.
Re: "memory full"
Some of us use an external drive, jump drive or a computer to save at least some of our photos. Also, It is wise to always have at least one back-up of all our photos .
Eg: If you have a Mac or PC:
Transfer photos and videos from your iPhone or iPad to your Mac or PC
Tip: Check out all the various ways you can do this, so you can choose.
and
How to back up your iPhone, iPad, and iPod touch - Apple Support
(some may choose iCloud, many prefer to keep all on computer or externally)
or
For Mac: Backup disks you can use with Time Machine - Apple Support
With everything backed-up you could then streamline the storage on your iPhone,
knowing you can retrieve anything if it becomes necessary.
How to check the storage on your iPhone, iPad, and iPod touch - Apple Support
NB: See: "Manage space on your iPhone, iPad, or iPod touch" in article below:
If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support
Re: "even if I delete a photo or application the memory drops more dps it goes up again could someone help me with this"
When a photo is deleted it generally goes to the "Recently Deleted" folder for 30 days, in case you want to recover it. So it still takes up the storage space.
To recover the space:
You can permanently delete the photos in "Recently Deleted" but they are then gone forever. (Photos > Albums, and tap Recently Deleted in the Utilities section. Is wise to back-up everything before deleting.)
Also: you may need to "Restart" your iPhone to see the change in storage space.
Hope there is something helpful to you here :-)