You don't need to save each copy in imagetoolbox. It does have tools spread across and may not be the UI you like. But, it works and also had a draw tool like you mentioned.
For a free drawing app with 1-time purchase, Ibis paint,
Inapp-purchases and play pass: Infinite painter
Foss draw apps: fossify paint
For memes there's memetastic which is Foss.